/* ========================================
   Academic AI - Premium Modern Styles
   ======================================== */

/* CSS Variables */
:root {
    --color-primary: #3B82F6;
    --color-primary-dark: #2563EB;
    --color-primary-light: #60A5FA;
    --color-primary-darker: #1D4ED8;
    --color-secondary: #6366F1;
    --color-text: #0F172A;
    --color-text-secondary: #334155;
    --color-text-light: #64748B;
    --color-text-muted: #94A3B8;
    --color-bg: #FAFAFA;
    --color-bg-alt: #F8FAFC;
    --color-white: #FFFFFF;
    --color-border: #E2E8F0;
    --color-border-light: #F1F5F9;
    --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.02);
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.04), 0 1px 2px rgba(0, 0, 0, 0.02);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.04), 0 2px 4px -1px rgba(0, 0, 0, 0.02);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.06), 0 4px 6px -2px rgba(0, 0, 0, 0.02);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.08), 0 10px 10px -5px rgba(0, 0, 0, 0.02);
    --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.12);
    --shadow-glow: 0 0 40px rgba(14, 165, 233, 0.15);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --radius-xl: 28px;
    --radius-full: 9999px;
    --transition-fast: 0.15s ease;
    --transition-base: 0.25s ease;
    --transition-slow: 0.4s ease;
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --container-width: 1200px;
    --header-height: 72px;
}

/* Reset & Base */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    font-size: 16px;
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

a {
    color: inherit;
    text-decoration: none;
    transition: all var(--transition-fast);
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

ul, ol {
    list-style: none;
}

/* Container */
.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 24px;
}

/* ========================================
   Buttons
   ======================================== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    padding: 14px 28px;
    font-size: 15px;
    font-weight: 600;
    border-radius: var(--radius-md);
    border: none;
    cursor: pointer;
    transition: all var(--transition-base);
    white-space: nowrap;
}

.btn-icon {
    width: 20px;
    height: 20px;
}

.btn-primary {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
    color: white;
    box-shadow: 0 4px 14px rgba(14, 165, 233, 0.35);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(14, 165, 233, 0.45);
}

.btn-secondary {
    background: var(--color-white);
    color: var(--color-text);
    border: 1px solid var(--color-border);
}

.btn-secondary:hover {
    background: var(--color-bg-alt);
    border-color: var(--color-text-light);
}

.btn-outline {
    background: transparent;
    color: var(--color-primary);
    border: 2px solid var(--color-primary);
}

.btn-outline:hover {
    background: var(--color-primary);
    color: white;
}

.btn-lg {
    padding: 18px 36px;
    font-size: 17px;
}

.btn-full {
    width: 100%;
}

/* ========================================
   Header
   ======================================== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height);
    background: rgba(255, 255, 255, 0.85);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--color-border-light);
    z-index: 1000;
    transition: all var(--transition-base);
}

.nav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: var(--header-height);
    gap: 32px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    font-weight: 700;
    font-size: 20px;
    color: var(--color-text);
}

.logo-img {
    width: 40px;
    height: 40px;
    object-fit: contain;
}

.logo-icon {
    width: 40px;
    height: 40px;
    border-radius: var(--radius-md);
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 4px;
    flex: 1;
    justify-content: center;
}

.nav-link {
    padding: 10px 18px;
    font-size: 14px;
    font-weight: 500;
    color: var(--color-text-light);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.nav-link:hover {
    color: var(--color-primary);
    background: rgba(59, 130, 246, 0.06);
}

/* Dropdown Menu */
.nav-dropdown {
    position: relative;
}

.nav-dropdown-toggle {
    display: flex;
    align-items: center;
    gap: 6px;
    background: none;
    border: none;
    cursor: pointer;
}

.nav-dropdown-toggle svg {
    width: 16px;
    height: 16px;
    transition: transform var(--transition-fast);
}

.nav-dropdown:hover .nav-dropdown-toggle svg {
    transform: rotate(180deg);
}

.nav-dropdown-menu {
    position: absolute;
    top: calc(100% + 12px);
    left: 0;
    min-width: 240px;
    background: var(--color-white);
    border: 1px solid var(--color-border-light);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-xl);
    padding: 8px;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all var(--transition-base);
    z-index: 100;
}

.nav-dropdown:hover .nav-dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.nav-dropdown-item {
    display: block;
    padding: 10px 14px;
    font-size: 14px;
    color: var(--color-text-secondary);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

.nav-dropdown-item:hover {
    background: rgba(59, 130, 246, 0.06);
    color: var(--color-primary);
}

.nav-dropdown-all {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-top: 4px;
    padding-top: 12px;
    border-top: 1px solid var(--color-border-light);
    font-weight: 600;
    color: var(--color-primary);
}

.nav-dropdown-all svg {
    width: 16px;
    height: 16px;
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 12px;
}

.mobile-menu-btn {
    display: none;
    width: 44px;
    height: 44px;
    padding: 10px;
    background: none;
    border: none;
    cursor: pointer;
    color: var(--color-text);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.mobile-menu-btn:hover {
    background: var(--color-bg-alt);
}

.mobile-menu-btn svg {
    width: 100%;
    height: 100%;
}

/* ========================================
   Mobile Menu
   ======================================== */
.mobile-menu {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--color-white);
    z-index: 2000;
    transform: translateX(100%);
    transition: transform 0.3s ease;
}

.mobile-menu.active {
    transform: translateX(0);
}

.mobile-menu-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 24px;
    border-bottom: 1px solid var(--color-border-light);
}

.mobile-menu-close {
    width: 44px;
    height: 44px;
    padding: 10px;
    background: none;
    border: none;
    cursor: pointer;
    color: var(--color-text);
    border-radius: var(--radius-md);
}

.mobile-menu-close svg {
    width: 100%;
    height: 100%;
}

.mobile-menu-nav {
    padding: 24px;
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.mobile-nav-link {
    padding: 16px 20px;
    font-size: 17px;
    font-weight: 500;
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.mobile-nav-link:hover {
    background: var(--color-bg-alt);
    color: var(--color-primary);
}

/* ========================================
   Hero Section
   ======================================== */
.hero {
    padding: calc(var(--header-height) + 80px) 0 80px;
    background: var(--color-bg);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -20%;
    width: 80%;
    height: 150%;
    background: radial-gradient(ellipse, rgba(14, 165, 233, 0.06) 0%, transparent 70%);
    pointer-events: none;
}

.hero::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 1px;
    background: linear-gradient(90deg, transparent 0%, var(--color-border) 50%, transparent 100%);
}

.hero .container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
    position: relative;
    z-index: 1;
}

.hero-content {
    max-width: 540px;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 8px 16px;
    background: rgba(14, 165, 233, 0.08);
    border-radius: var(--radius-full);
    font-size: 13px;
    font-weight: 600;
    color: var(--color-primary);
    margin-bottom: 24px;
}

.hero-title {
    font-size: 52px;
    font-weight: 700;
    line-height: 1.15;
    margin-bottom: 20px;
    color: var(--color-text);
    letter-spacing: -0.02em;
}

.hero-title span {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 18px;
    color: var(--color-text-secondary);
    margin-bottom: 32px;
    line-height: 1.7;
}

.hero-actions {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 16px;
    margin-bottom: 32px;
}

.hero-trial {
    font-size: 14px;
    color: var(--color-text-muted);
    display: flex;
    align-items: center;
    gap: 6px;
}

.hero-trial::before {
    content: '✓';
    width: 18px;
    height: 18px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(14, 165, 233, 0.1);
    border-radius: 50%;
    font-size: 10px;
    color: var(--color-primary);
}

.hero-pricing {
    display: inline-flex;
    align-items: baseline;
    gap: 8px;
    padding: 12px 20px;
    background: var(--color-white);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--color-border-light);
}

.hero-pricing .price {
    font-size: 36px;
    font-weight: 700;
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-pricing .period {
    font-size: 16px;
    color: var(--color-text-light);
}

/* Hero Preview */
.hero-image {
    position: relative;
}

.hero-image::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 120%;
    height: 120%;
    background: radial-gradient(ellipse, rgba(14, 165, 233, 0.12) 0%, transparent 70%);
    pointer-events: none;
}

.hero-preview {
    background: var(--color-white);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-2xl), var(--shadow-glow);
    overflow: hidden;
    border: 1px solid var(--color-border-light);
    position: relative;
    z-index: 1;
}

.preview-header {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 16px 20px;
    background: var(--color-bg-alt);
    border-bottom: 1px solid var(--color-border-light);
}

.preview-dots {
    display: flex;
    gap: 6px;
}

.preview-dots span {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: var(--color-border);
}

.preview-dots span:first-child { background: #EF4444; }
.preview-dots span:nth-child(2) { background: #F59E0B; }
.preview-dots span:last-child { background: #22C55E; }

.preview-title {
    font-size: 13px;
    color: var(--color-text-light);
    font-weight: 500;
}

.preview-content {
    padding: 20px;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.preview-message {
    max-width: 88%;
    padding: 14px 18px;
    border-radius: var(--radius-md);
    font-size: 14px;
    line-height: 1.6;
    box-shadow: var(--shadow-xs);
}

.preview-message.bot {
    background: var(--color-bg-alt);
    align-self: flex-start;
    border-bottom-left-radius: 6px;
    border: 1px solid var(--color-border-light);
}

.preview-message.user {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
    color: white;
    align-self: flex-end;
    border-bottom-right-radius: 6px;
    box-shadow: 0 4px 12px rgba(14, 165, 233, 0.3);
}

.preview-message ol {
    margin-left: 20px;
    margin-top: 10px;
}

/* ========================================
   Stats Section
   ======================================== */
.stats-section {
    padding: 48px 0;
    background: var(--color-white);
    border-bottom: 1px solid var(--color-border-light);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 32px;
}

.stat-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
    padding: 24px;
    background: var(--color-bg);
    border-radius: var(--radius-lg);
    border: 1px solid var(--color-border-light);
    transition: all var(--transition-base);
}

.stat-item:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--color-primary-light);
}

.stat-number {
    font-size: 36px;
    font-weight: 700;
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    font-size: 14px;
    color: var(--color-text-light);
    font-weight: 500;
}

/* ========================================
   Features Section
   ======================================== */
.features {
    padding: 80px 0;
    background: var(--color-bg);
}

.section-header {
    text-align: center;
    max-width: 600px;
    margin: 0 auto 48px;
}

.section-label {
    display: inline-block;
    padding: 6px 14px;
    background: rgba(14, 165, 233, 0.08);
    border-radius: var(--radius-full);
    font-size: 13px;
    font-weight: 600;
    color: var(--color-primary);
    margin-bottom: 16px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.section-title {
    font-size: 32px;
    font-weight: 700;
    color: var(--color-text);
    margin-bottom: 16px;
    letter-spacing: -0.02em;
}

.section-subtitle {
    font-size: 16px;
    color: var(--color-text-light);
    line-height: 1.7;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
}

.feature-card {
    padding: 28px;
    background: var(--color-white);
    border: 1px solid var(--color-border-light);
    border-radius: var(--radius-lg);
    text-align: center;
    transition: all var(--transition-base);
}

.feature-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-xl);
    border-color: transparent;
}

.feature-icon {
    width: 56px;
    height: 56px;
    margin: 0 auto 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, rgba(14, 165, 233, 0.1) 0%, rgba(6, 182, 212, 0.1) 100%);
    border-radius: var(--radius-md);
    color: var(--color-primary);
}

.feature-icon svg {
    width: 26px;
    height: 26px;
}

.feature-title {
    font-size: 17px;
    font-weight: 600;
    margin-bottom: 10px;
    color: var(--color-text);
}

.feature-desc {
    font-size: 14px;
    color: var(--color-text-light);
    line-height: 1.6;
}

/* ========================================
   Subjects Section
   ======================================== */
.subjects {
    padding: 80px 0;
    background: var(--color-white);
}

.subjects-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 20px;
}

.subject-card {
    padding: 24px;
    background: var(--color-bg);
    border: 1px solid var(--color-border-light);
    border-radius: var(--radius-lg);
    transition: all var(--transition-base);
    display: flex;
    flex-direction: column;
    align-items: flex-start;
}

.subject-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--color-primary-light);
    background: var(--color-white);
}

.subject-icon {
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--color-white);
    border-radius: var(--radius-md);
    color: var(--color-primary);
    margin-bottom: 16px;
    box-shadow: var(--shadow-sm);
}

.subject-icon svg {
    width: 22px;
    height: 22px;
}

.subject-title {
    font-size: 18px;
    font-weight: 600;
    color: var(--color-text);
    text-align: center;
    width: 100%;
}

.subject-desc {
    font-size: 13px;
    color: var(--color-text-light);
    text-align: center;
    line-height: 1.5;
    margin-top: 8px;
    margin-bottom: auto;
}

.subject-link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-size: 13px;
    font-weight: 600;
    color: var(--color-primary);
    margin-top: 16px;
    padding-top: 12px;
    border-top: 1px solid var(--color-border-light);
    width: 100%;
}

.subject-link svg {
    width: 16px;
    height: 16px;
    transition: transform var(--transition-fast);
}

.subject-card:hover .subject-link svg {
    transform: translateX(4px);
}

/* Compact subject cards (home) */
.subjects-grid-compact {
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    gap: 12px;
}

.subject-card-compact {
    padding: 16px 20px;
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
}

.subject-card-compact:hover {
    transform: translateY(-2px);
}

.subject-card-title {
    font-size: 15px;
    font-weight: 600;
    color: var(--color-text);
}

.subject-card-compact:hover .subject-card-title {
    color: var(--color-primary);
}

.subject-card-arrow {
    width: 16px;
    height: 16px;
    color: var(--color-text-muted);
    flex-shrink: 0;
    transition: transform var(--transition-fast), color var(--transition-fast);
}

.subject-card-compact:hover .subject-card-arrow {
    color: var(--color-primary);
    transform: translateX(2px);
}

/* ========================================
   How It Works Section
   ======================================== */
.how-it-works {
    padding: 80px 0;
    background: var(--color-bg);
}

.steps-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 32px;
    position: relative;
}

.steps-grid::before {
    content: '';
    position: absolute;
    top: 48px;
    left: 20%;
    right: 20%;
    height: 2px;
    background: linear-gradient(90deg, var(--color-border-light) 0%, var(--color-primary-light) 50%, var(--color-border-light) 100%);
    z-index: 0;
}

.step-card {
    padding: 32px;
    background: var(--color-white);
    border-radius: var(--radius-lg);
    text-align: center;
    position: relative;
    z-index: 1;
    border: 1px solid var(--color-border-light);
}

.step-number {
    width: 56px;
    height: 56px;
    margin: 0 auto 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
    color: white;
    font-size: 22px;
    font-weight: 700;
    border-radius: 50%;
    box-shadow: 0 4px 16px rgba(14, 165, 233, 0.35);
}

.step-title {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 10px;
    color: var(--color-text);
}

.step-desc {
    font-size: 14px;
    color: var(--color-text-light);
    line-height: 1.6;
}

/* ========================================
   Pricing Section
   ======================================== */
.pricing-section {
    padding: 80px 0;
    background: var(--color-white);
}

.pricing-card {
    max-width: 440px;
    margin: 0 auto;
    background: var(--color-bg);
    border-radius: var(--radius-xl);
    overflow: hidden;
    border: 1px solid var(--color-border-light);
    box-shadow: var(--shadow-xl);
}

.pricing-header {
    padding: 40px;
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
    text-align: center;
}

.pricing-title {
    font-size: 26px;
    font-weight: 700;
    color: white;
    margin-bottom: 6px;
}

.pricing-subtitle {
    font-size: 15px;
    color: rgba(255, 255, 255, 0.9);
}

.pricing-body {
    padding: 40px;
}

.pricing-price {
    text-align: center;
    margin-bottom: 32px;
}

.pricing-price .price {
    font-size: 56px;
    font-weight: 700;
    color: var(--color-text);
    letter-spacing: -0.02em;
}

.pricing-price .period {
    font-size: 18px;
    color: var(--color-text-light);
}

.pricing-features {
    margin-bottom: 32px;
}

.pricing-features li {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 14px 0;
    font-size: 15px;
    color: var(--color-text-secondary);
    border-bottom: 1px solid var(--color-border-light);
}

.pricing-features li:last-child {
    border-bottom: none;
}

.pricing-features svg {
    width: 22px;
    height: 22px;
    color: var(--color-primary);
    flex-shrink: 0;
}

.pricing-trial {
    text-align: center;
    font-size: 14px;
    color: var(--color-text-muted);
    margin-top: 20px;
    padding-top: 20px;
    border-top: 1px solid var(--color-border-light);
}

/* ========================================
   FAQ Section
   ======================================== */
.faq-section {
    padding: 80px 0;
    background: var(--color-bg);
}

.faq-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
    max-width: 1000px;
    margin: 0 auto;
}

.faq-item {
    padding: 28px;
    background: var(--color-white);
    border-radius: var(--radius-lg);
    border: 1px solid var(--color-border-light);
    transition: all var(--transition-base);
}

.faq-item:hover {
    box-shadow: var(--shadow-md);
    border-color: var(--color-primary-light);
}

.faq-question {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 10px;
    color: var(--color-text);
    display: flex;
    align-items: flex-start;
    gap: 12px;
}

.faq-question::before {
    content: 'Q';
    width: 24px;
    height: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(14, 165, 233, 0.1);
    color: var(--color-primary);
    font-size: 12px;
    font-weight: 700;
    border-radius: 6px;
    flex-shrink: 0;
}

.faq-answer {
    font-size: 14px;
    color: var(--color-text-light);
    line-height: 1.7;
    padding-left: 36px;
}

/* ========================================
   Final CTA Section
   ======================================== */
.final-cta {
    padding: 80px 0;
    background: var(--color-white);
}

.final-cta-content {
    text-align: center;
    max-width: 560px;
    margin: 0 auto;
    padding: 48px;
    background: linear-gradient(135deg, rgba(14, 165, 233, 0.05) 0%, rgba(6, 182, 212, 0.05) 100%);
    border-radius: var(--radius-xl);
    border: 1px solid rgba(14, 165, 233, 0.1);
}

.final-cta-title {
    font-size: 30px;
    font-weight: 700;
    margin-bottom: 14px;
    color: var(--color-text);
    letter-spacing: -0.02em;
}

.final-cta-text {
    font-size: 16px;
    color: var(--color-text-light);
    margin-bottom: 28px;
    line-height: 1.7;
}

/* ========================================
   Category Header
   ======================================== */
.category-header {
    padding: calc(var(--header-height) + 56px) 0 40px;
    background: var(--color-bg);
    text-align: center;
    border-bottom: 1px solid var(--color-border-light);
}

.category-title {
    font-size: 40px;
    font-weight: 700;
    margin-bottom: 14px;
    color: var(--color-text);
    letter-spacing: -0.02em;
}

.category-description {
    font-size: 17px;
    color: var(--color-text-light);
    max-width: 600px;
    margin: 0 auto;
    line-height: 1.7;
}

/* ========================================
   Breadcrumbs
   ======================================== */
.breadcrumbs {
    padding: 16px 0;
    background: var(--color-white);
    border-bottom: 1px solid var(--color-border-light);
    margin-top: var(--header-height);
}

.breadcrumbs-top {
    position: sticky;
    top: var(--header-height);
    z-index: 900;
    background: rgba(255, 255, 255, 0.92);
    backdrop-filter: blur(10px);
}

.breadcrumb-list {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 14px;
}

.breadcrumb-item {
    color: var(--color-text-light);
}

.breadcrumb-item a:hover {
    color: var(--color-primary);
}

.breadcrumb-item::after {
    content: '/';
    margin-left: 8px;
    color: var(--color-text-muted);
}

.breadcrumb-item:last-child::after {
    display: none;
}

.breadcrumb-item.active {
    color: var(--color-text);
}

.section-heading {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 12px;
}

/* ========================================
   Category Content
   ======================================== */
.category-content {
    padding: 56px 0;
}

.content-wrapper {
    display: grid;
    grid-template-columns: 1fr 340px;
    gap: 48px;
}

.content-main {
    min-width: 0;
}

.category-full-content {
    font-size: 16px;
    line-height: 1.8;
}

.category-seo-text {
    margin-top: 32px;
    padding-top: 32px;
    border-top: 1px solid var(--color-border-light);
    font-size: 15px;
    line-height: 1.8;
    color: var(--color-text-secondary);
    margin-bottom: 48px;
}

.category-full-content h2 {
    font-size: 22px;
    font-weight: 600;
    margin-bottom: 16px;
    color: var(--color-text);
}

.category-full-content h3 {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--color-text);
}

.category-full-content p {
    margin-bottom: 16px;
}

.category-full-content ul,
.category-full-content ol {
    margin-bottom: 16px;
    padding-left: 24px;
}

.category-full-content li {
    margin-bottom: 8px;
    list-style: disc;
}

.section-subtitle {
    font-size: 22px;
    font-weight: 600;
    margin-bottom: 24px;
    color: var(--color-text);
}

/* Sidebar */
.content-sidebar {
    display: flex;
    flex-direction: column;
    gap: 24px;
}

.sidebar-card {
    padding: 24px;
    background: var(--color-white);
    border: 1px solid var(--color-border-light);
    border-radius: var(--radius-lg);
}

.sidebar-title {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--color-text);
}

.sidebar-text {
    font-size: 14px;
    color: var(--color-text-light);
    margin-bottom: 16px;
    line-height: 1.6;
}

.sidebar-price {
    font-size: 24px;
    font-weight: 700;
    color: var(--color-primary);
    text-align: center;
    margin-top: 16px;
    padding-top: 16px;
    border-top: 1px solid var(--color-border-light);
}

.steps-list {
    counter-reset: steps;
    list-style: none;
    padding: 0;
}

.steps-list li {
    position: relative;
    padding-left: 32px;
    margin-bottom: 12px;
    font-size: 14px;
    color: var(--color-text-light);
    counter-increment: steps;
}

.steps-list li::before {
    content: counter(steps);
    position: absolute;
    left: 0;
    width: 20px;
    height: 20px;
    background: var(--color-primary);
    color: white;
    border-radius: 50%;
    font-size: 11px;
    font-weight: 600;
    display: flex;
    align-items: center;
    justify-content: center;
}

.benefits-list {
    list-style: none;
    padding: 0;
}

.benefits-list li {
    position: relative;
    padding-left: 24px;
    margin-bottom: 12px;
    font-size: 14px;
    color: var(--color-text-light);
}

.benefits-list li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--color-primary);
    font-weight: 600;
}

.related-list {
    list-style: none;
    padding: 0;
}

.related-list li {
    margin-bottom: 8px;
}

.related-list a {
    font-size: 14px;
    color: var(--color-text-light);
    transition: color var(--transition-fast);
}

.related-list a:hover {
    color: var(--color-primary);
}

/* ========================================
   Contacts Section
   ======================================== */
.contacts-section {
    padding: 56px 0;
}

.contacts-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
    margin-bottom: 56px;
}

.contact-card {
    padding: 28px;
    background: var(--color-white);
    border: 1px solid var(--color-border-light);
    border-radius: var(--radius-lg);
    text-align: center;
    transition: all var(--transition-base);
}

.contact-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.contact-icon {
    width: 60px;
    height: 60px;
    margin: 0 auto 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, rgba(14, 165, 233, 0.1) 0%, rgba(6, 182, 212, 0.1) 100%);
    border-radius: var(--radius-md);
    color: var(--color-primary);
}

.contact-icon svg {
    width: 30px;
    height: 30px;
}

.contact-title {
    font-size: 17px;
    font-weight: 600;
    margin-bottom: 8px;
}

.contact-link {
    font-size: 15px;
    color: var(--color-primary);
    font-weight: 500;
    display: block;
    margin-bottom: 6px;
}

.contact-text {
    font-size: 15px;
    font-weight: 500;
    color: var(--color-text);
    display: block;
    margin-bottom: 6px;
}

.contact-desc {
    font-size: 13px;
    color: var(--color-text-muted);
}

.contacts-cta {
    text-align: center;
    padding: 56px;
    background: var(--color-bg);
    border-radius: var(--radius-xl);
}

.contacts-cta-title {
    font-size: 26px;
    font-weight: 700;
    margin-bottom: 12px;
}

.contacts-cta-text {
    font-size: 16px;
    color: var(--color-text-light);
    margin-bottom: 24px;
}

/* ========================================
   Privacy Section
   ======================================== */
.privacy-section {
    padding: 56px 0;
}

.privacy-content {
    max-width: 800px;
    margin: 0 auto;
}

.privacy-content h2 {
    font-size: 20px;
    font-weight: 600;
    margin-top: 36px;
    margin-bottom: 14px;
    color: var(--color-text);
}

.privacy-content h2:first-child {
    margin-top: 0;
}

.privacy-content p {
    margin-bottom: 14px;
    color: var(--color-text-light);
    line-height: 1.7;
}

.privacy-content ul {
    margin-bottom: 14px;
    padding-left: 24px;
}

.privacy-content li {
    margin-bottom: 8px;
    color: var(--color-text-light);
    list-style: disc;
}

.privacy-date {
    margin-top: 36px;
    font-size: 14px;
    color: var(--color-text-muted);
}

/* ========================================
   Blog - Hub & Article (Redesigned)
   ======================================== */

/* Blog Hero */
.blog-hero {
    padding: 24px 0 48px;
    background: radial-gradient(circle at top right, rgba(99, 102, 241, 0.06) 0%, transparent 40%),
                radial-gradient(circle at bottom left, rgba(59, 130, 246, 0.06) 0%, transparent 40%);
}

.blog-hero-content {
    max-width: 640px;
}

.blog-hero-title {
    font-size: 42px;
    font-weight: 800;
    line-height: 1.15;
    margin-bottom: 16px;
    color: var(--color-text);
    letter-spacing: -0.02em;
}

.blog-hero-subtitle {
    font-size: 18px;
    color: var(--color-text-secondary);
    line-height: 1.7;
}

.blog-section-title {
    font-size: 22px;
    font-weight: 700;
    color: var(--color-text);
    margin-bottom: 24px;
}

/* Blog Featured */
.blog-featured {
    padding: 0 0 56px;
}

.blog-featured-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.blog-featured-card {
    display: flex;
    flex-direction: column;
    background: var(--color-white);
    border: 1px solid var(--color-border-light);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: all var(--transition-base);
}

.blog-featured-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
    border-color: transparent;
}

.blog-featured-image {
    aspect-ratio: 16/10;
    overflow: hidden;
    background: var(--color-bg);
}

.blog-featured-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--transition-slow);
}

.blog-featured-card:hover .blog-featured-image img {
    transform: scale(1.03);
}

.blog-featured-image-placeholder {
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-border);
}

.blog-featured-image-placeholder svg {
    width: 48px;
    height: 48px;
}

.blog-featured-body {
    padding: 24px;
    display: flex;
    flex-direction: column;
    flex: 1;
}

.blog-featured-title {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 10px;
    line-height: 1.4;
    color: var(--color-text);
}

.blog-featured-excerpt {
    font-size: 14px;
    color: var(--color-text-light);
    line-height: 1.6;
    margin-bottom: 16px;
    flex: 1;
}

/* Blog Posts Grid */
.blog-list-section {
    padding: 0 0 80px;
}

.blog-posts-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.blog-post-card {
    display: flex;
    flex-direction: column;
    background: var(--color-white);
    border: 1px solid var(--color-border-light);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: all var(--transition-base);
}

.blog-post-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--color-primary-light);
}

.blog-post-card-image {
    aspect-ratio: 16/10;
    overflow: hidden;
    background: var(--color-bg);
}

.blog-post-card-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--transition-slow);
}

.blog-post-card:hover .blog-post-card-image img {
    transform: scale(1.03);
}

.blog-post-card-image-placeholder {
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-border);
}

.blog-post-card-image-placeholder svg {
    width: 40px;
    height: 40px;
}

.blog-post-card-body {
    padding: 24px;
    display: flex;
    flex-direction: column;
    flex: 1;
}

.blog-card-date {
    font-size: 13px;
    color: var(--color-text-muted);
    margin-bottom: 12px;
}

.blog-post-card-title {
    font-size: 17px;
    font-weight: 600;
    margin-bottom: 10px;
    line-height: 1.4;
    color: var(--color-text);
}

.blog-post-card-excerpt {
    font-size: 14px;
    color: var(--color-text-light);
    line-height: 1.6;
    margin-bottom: 16px;
    flex: 1;
}

.blog-card-link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-size: 14px;
    font-weight: 600;
    color: var(--color-primary);
}

.blog-card-link svg {
    width: 16px;
    height: 16px;
    transition: transform var(--transition-fast);
}

.blog-post-card:hover .blog-card-link svg {
    transform: translateX(4px);
}

.blog-empty {
    grid-column: 1 / -1;
    text-align: center;
    padding: 80px 24px;
    color: var(--color-text-light);
    background: var(--color-white);
    border-radius: var(--radius-lg);
    border: 1px solid var(--color-border-light);
}

/* Legacy (keep for backwards compat) */
.featured-posts { margin-bottom: 56px; }
.featured-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 28px; }
.featured-card { display: grid; grid-template-columns: 200px 1fr; background: var(--color-white); border: 1px solid var(--color-border-light); border-radius: var(--radius-lg); overflow: hidden; }
.featured-image { aspect-ratio: 1; overflow: hidden; }
.featured-content { padding: 24px; }
.featured-title { font-size: 18px; font-weight: 600; }
.featured-excerpt { font-size: 14px; color: var(--color-text-light); }
.featured-link { display: inline-flex; align-items: center; gap: 6px; font-size: 14px; font-weight: 600; color: var(--color-primary); }
.posts-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.no-posts { grid-column: 1 / -1; text-align: center; padding: 56px; }

/* ========================================
   Article Detail (Post)
   ======================================== */
.article-detail {
    padding-bottom: 0;
}

.article-hero {
    padding: 24px 0 48px;
    background: radial-gradient(circle at top right, rgba(99, 102, 241, 0.06) 0%, transparent 40%),
                radial-gradient(circle at bottom left, rgba(59, 130, 246, 0.06) 0%, transparent 40%);
}

.article-hero-inner {
    max-width: 800px;
}

.article-date {
    font-size: 14px;
    color: var(--color-text-muted);
    display: block;
    margin-bottom: 16px;
}

.article-title {
    font-size: 42px;
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: 20px;
    color: var(--color-text);
    letter-spacing: -0.02em;
}

.article-lead {
    font-size: 20px;
    color: var(--color-text-secondary);
    line-height: 1.7;
    margin-bottom: 32px;
}

.article-hero-image {
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-lg);
}

.article-hero-image img {
    width: 100%;
}

/* Article inline CTA */
.article-cta-inline {
    padding: 0 0 48px;
}

.article-cta-box {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
    padding: 24px 32px;
    background: linear-gradient(135deg, rgba(59, 130, 246, 0.08) 0%, rgba(99, 102, 241, 0.08) 100%);
    border-radius: var(--radius-lg);
    border: 1px solid rgba(59, 130, 246, 0.2);
}

.article-cta-text {
    font-size: 17px;
    font-weight: 600;
    color: var(--color-text);
}

.article-content {
    padding: 48px 0 80px;
}

.article-layout {
    display: grid;
    grid-template-columns: 220px 1fr;
    gap: 48px;
    align-items: start;
}

.article-toc {
    position: sticky;
    top: calc(var(--header-height) + 24px);
}

.article-toc-toggle {
    display: flex;
    align-items: center;
    justify-content: space-between;
    width: 100%;
    padding: 12px 16px;
    font-size: 14px;
    font-weight: 600;
    color: var(--color-text);
    background: var(--color-bg);
    border: 1px solid var(--color-border-light);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.article-toc-toggle:hover {
    border-color: var(--color-primary-light);
}

.article-toc-chevron {
    width: 16px;
    height: 16px;
    transition: transform var(--transition-fast);
}

.article-toc[data-open] .article-toc-chevron {
    transform: rotate(180deg);
}

.article-toc-list {
    display: none;
    flex-direction: column;
    gap: 4px;
    margin-top: 12px;
    padding: 16px;
    background: var(--color-bg);
    border: 1px solid var(--color-border-light);
    border-radius: var(--radius-md);
}

.article-toc[data-open] .article-toc-list {
    display: flex;
}

.article-toc-link {
    font-size: 13px;
    color: var(--color-text-secondary);
    padding: 6px 0;
    transition: color var(--transition-fast);
}

.article-toc-link:hover {
    color: var(--color-primary);
}

.article-toc-link-3 {
    padding-left: 16px;
}

.article-body {
    max-width: 720px;
    font-size: 18px;
    line-height: 1.8;
    color: var(--color-text-secondary);
}

.article-body h2 {
    font-size: 28px;
    font-weight: 700;
    margin-top: 48px;
    margin-bottom: 16px;
    color: var(--color-text);
}

.article-body h3 {
    font-size: 22px;
    font-weight: 600;
    margin-top: 36px;
    margin-bottom: 12px;
    color: var(--color-text);
}

.article-body p {
    margin-bottom: 20px;
}

.article-body ul,
.article-body ol {
    margin-bottom: 20px;
    padding-left: 28px;
}

.article-body li {
    margin-bottom: 10px;
}

.article-body ul li { list-style: disc; }
.article-body ol li { list-style: decimal; }

/* Article Related */
.article-related {
    padding: 56px 0;
    background: var(--color-bg);
}

.article-related-title {
    font-size: 22px;
    font-weight: 700;
    color: var(--color-text);
    margin-bottom: 24px;
}

.article-related-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.article-related-card {
    display: flex;
    flex-direction: column;
    background: var(--color-white);
    border: 1px solid var(--color-border-light);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: all var(--transition-base);
}

.article-related-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.article-related-image {
    aspect-ratio: 16/10;
    overflow: hidden;
    background: var(--color-bg);
}

.article-related-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.article-related-image-placeholder {
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-border);
}

.article-related-image-placeholder svg {
    width: 40px;
    height: 40px;
}

.article-related-body {
    padding: 20px;
}

.article-related-card-title {
    font-size: 16px;
    font-weight: 600;
    line-height: 1.4;
    color: var(--color-text);
}

.article-related-card:hover .article-related-card-title {
    color: var(--color-primary);
}

/* Legacy post styles */
.post-detail { padding-bottom: 56px; }
.post-header { padding: 40px 0; background: var(--color-bg); }
.post-date { font-size: 14px; color: var(--color-text-muted); }
.post-title { font-size: 40px; font-weight: 700; }
.post-excerpt { font-size: 18px; color: var(--color-text-light); }
.post-image { max-width: 900px; margin: 0 auto; }
.post-content { padding: 56px 0; }
.post-body { max-width: 720px; margin: 0 auto; font-size: 16px; }
.related-posts { padding: 56px 0; }
.related-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.related-card { background: var(--color-white); border-radius: var(--radius-md); }
.related-image { aspect-ratio: 16/10; }
.related-content { padding: 18px; }
.related-date {
    font-size: 12px;
    color: var(--color-text-muted);
    display: block;
    margin-bottom: 6px;
}

.related-title {
    font-size: 15px;
    font-weight: 600;
    margin-bottom: 6px;
    line-height: 1.4;
    color: var(--color-text);
}

.related-title a:hover {
    color: var(--color-primary);
}

.related-excerpt {
    font-size: 13px;
    color: var(--color-text-light);
    line-height: 1.5;
}

/* ========================================
   Footer
   ======================================== */
.footer {
    background: var(--color-text);
    color: white;
    padding: 64px 0 0;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 48px;
    margin-bottom: 56px;
}

.footer-brand {
    display: flex;
    flex-direction: column;
}

.footer-brand .logo {
    color: white;
    margin-bottom: 14px;
}

.footer-desc {
    font-size: 14px;
    color: rgba(255, 255, 255, 0.6);
    margin-bottom: 24px;
    line-height: 1.6;
}

.footer-brand .btn-secondary {
    background: rgba(255, 255, 255, 0.1);
    color: white;
    border-color: rgba(255, 255, 255, 0.15);
}

.footer-brand .btn-secondary:hover {
    background: rgba(255, 255, 255, 0.2);
}

.footer-brand .btn-secondary svg {
    color: #22C55E;
}

.footer-title {
    font-size: 15px;
    font-weight: 600;
    margin-bottom: 18px;
    color: white;
}

.footer-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.footer-list li a {
    font-size: 14px;
    color: rgba(255, 255, 255, 0.6);
    transition: all var(--transition-fast);
}

.footer-list li a:hover {
    color: white;
}

.footer-list svg {
    width: 16px;
    height: 16px;
    margin-right: 10px;
}

.footer-contacts .footer-list li {
    display: flex;
    align-items: center;
}

.footer-bottom {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 24px 0;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.copyright {
    font-size: 14px;
    color: rgba(255, 255, 255, 0.5);
}

.privacy-link {
    font-size: 14px;
    color: rgba(255, 255, 255, 0.6);
}

.privacy-link:hover {
    color: white;
}

/* Teachers Features */
.teachers-features {
    margin-top: 48px;
}

.teachers-features .features-grid {
    margin-bottom: 0;
}

/* Subjects List */
.subjects-list {
    margin-top: 48px;
}

/* SEO Text Section */
.seo-text-section {
    padding: 60px 0;
    background: var(--color-bg);
}

.seo-text-content {
    max-width: 900px;
    margin: 0 auto;
    font-size: 15px;
    line-height: 1.8;
    color: var(--color-text-secondary);
}

.seo-text-content h2 {
    font-size: 22px;
    font-weight: 600;
    margin-top: 32px;
    margin-bottom: 16px;
    color: var(--color-text);
}

.seo-text-content h2:first-child {
    margin-top: 0;
}

.seo-text-content h3 {
    font-size: 18px;
    font-weight: 600;
    margin-top: 24px;
    margin-bottom: 12px;
    color: var(--color-text);
}

.seo-text-content p {
    margin-bottom: 16px;
}

.seo-text-content ul,
.seo-text-content ol {
    margin-bottom: 16px;
    padding-left: 24px;
}

.seo-text-content li {
    margin-bottom: 8px;
    list-style: disc;
}

/* ========================================
   Responsive
   ======================================== */
@media (max-width: 1024px) {
    .hero .container {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-content {
        max-width: 100%;
    }
    
    .hero-actions {
        align-items: center;
    }
    
    .hero-pricing {
        justify-content: center;
    }
    
    .hero-image {
        max-width: 500px;
        margin: 0 auto;
    }
    
    .features-grid,
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .subjects-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .blog-featured-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .blog-posts-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .subjects-grid-compact {
        grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
    }
    
    .footer-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .contacts-grid {
        grid-template-columns: 1fr;
    }
    
    .featured-grid {
        grid-template-columns: 1fr;
    }
    
    .featured-card {
        grid-template-columns: 1fr;
    }
    
    .featured-image {
        aspect-ratio: 16/9;
    }
    
    .faq-grid {
        grid-template-columns: 1fr;
    }
    
    .steps-grid::before {
        display: none;
    }
}

@media (max-width: 768px) {
    :root {
        --header-height: 64px;
    }
    
    .nav-links,
    .nav-actions {
        display: none;
    }
    
    .mobile-menu-btn {
        display: block;
    }
    
    .hero {
        padding: calc(var(--header-height) + 48px) 0 56px;
    }
    
    .hero-title {
        font-size: 36px;
    }
    
    .hero-subtitle {
        font-size: 17px;
    }
    
    .section-title {
        font-size: 26px;
        margin-bottom: 36px;
    }
    
    .features-grid,
    .subjects-grid,
    .posts-grid,
    .related-grid,
    .steps-grid {
        grid-template-columns: 1fr;
    }
    
    .blog-hero-title {
        font-size: 28px;
    }
    
    .blog-hero-subtitle {
        font-size: 16px;
    }
    
    .blog-featured-grid,
    .blog-posts-grid,
    .article-related-grid {
        grid-template-columns: 1fr;
    }
    
    .article-title {
        font-size: 28px;
    }
    
    .article-lead {
        font-size: 17px;
    }
    
    .article-cta-box {
        flex-direction: column;
        text-align: center;
        padding: 20px;
    }
    
    .article-layout {
        grid-template-columns: 1fr;
    }
    
    .article-toc {
        position: static;
        margin-top: 0;
    }
    
    .article-hero {
        padding-bottom: 24px;
    }
    
    .article-cta-inline {
        padding-bottom: 24px;
    }
    
    .article-content {
        padding-top: 24px;
    }
    
    .subjects-grid-compact {
        grid-template-columns: repeat(2, 1fr);
        gap: 10px;
    }
    
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 16px;
    }
    
    .stat-item {
        padding: 20px;
    }
    
    .stat-number {
        font-size: 28px;
    }
    
    .content-wrapper {
        grid-template-columns: 1fr;
    }
    
    .footer-grid {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .footer-brand {
        align-items: center;
    }

    .footer-links,
    .footer-contacts {
        text-align: center;
    }

    .footer-list {
        align-items: center;
    }

    .footer-contacts .footer-list li {
        justify-content: center;
    }

    .footer-bottom {
        flex-direction: column;
        gap: 12px;
        text-align: center;
    }
    
    .category-title {
        font-size: 30px;
    }
    
    .post-title {
        font-size: 30px;
    }
    
    .breadcrumb-list {
        flex-wrap: wrap;
    }

    .breadcrumbs {
        margin-top: var(--header-height);
        padding: 10px 0;
    }

    .category-hero {
        padding: 16px 0 40px;
    }

    .category-hero-title {
        font-size: 34px;
        line-height: 1.15;
        margin-bottom: 16px;
    }

    .category-hero-subtitle {
        font-size: 16px;
        margin-bottom: 24px;
    }

    .category-badge {
        font-size: 12px;
        padding: 6px 12px;
        gap: 8px;
    }

    .hero-trial-text {
        flex-wrap: wrap;
        justify-content: center;
        text-align: center;
        gap: 6px;
    }

    .chat-interface-mockup {
        max-width: 100%;
        transform: none;
        border-radius: 18px;
    }

    .chat-messages {
        height: auto;
        padding: 16px;
    }

    .message {
        font-size: 14px;
    }

    .comparison-grid {
        margin-top: 24px;
        display: flex;
        flex-direction: column;
        gap: 16px;
    }

    .comparison-card {
        padding: 24px;
        border-radius: 18px;
        width: 100%;
    }

    .features-grid-large {
        gap: 20px;
        grid-template-columns: 1fr;
    }

    .feature-box {
        padding: 22px;
        border-radius: 16px;
        width: 100%;
    }

    .steps-row {
        margin-top: 32px;
        gap: 16px;
        width: 100%;
    }

    .step-arrow {
        display: none;
    }

    .content-wrapper {
        gap: 32px;
    }

    .sidebar-card {
        padding: 20px;
    }
}

/* ========================================
   Animations
   ======================================== */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes float {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-10px);
    }
}

.animate-fadeInUp {
    animation: fadeInUp 0.6s ease forwards;
}

.animate-float {
    animation: float 3s ease-in-out infinite;
}

/* Smooth scroll for anchor links */
html {
    scroll-padding-top: var(--header-height);
}

/* ========================================
   Redesigned Category/Subject Page
   ======================================== */
.category-hero {
    padding: 16px 0 80px;
    background: radial-gradient(circle at top right, rgba(99, 102, 241, 0.08) 0%, transparent 40%),
                radial-gradient(circle at bottom left, rgba(59, 130, 246, 0.08) 0%, transparent 40%);
    position: relative;
    overflow: hidden;
}

.category-hero .container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
    position: relative;
    z-index: 1;
}

.category-hero-content {
    max-width: 600px;
}

.category-badge {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    padding: 8px 16px;
    background: white;
    border: 1px solid var(--color-border-light);
    border-radius: var(--radius-full);
    font-size: 14px;
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: 32px;
    box-shadow: var(--shadow-sm);
}

.category-icon-wrapper {
    width: 24px;
    height: 24px;
    color: var(--color-primary);
}

.category-hero-title {
    font-size: 56px;
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: 24px;
    color: var(--color-text);
    letter-spacing: -0.03em;
}

.category-hero-subtitle {
    font-size: 20px;
    color: var(--color-text-secondary);
    margin-bottom: 40px;
    line-height: 1.6;
}

.category-hero-actions {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.hero-trial-text {
    font-size: 14px;
    color: var(--color-text-muted);
    display: flex;
    align-items: center;
    gap: 8px;
}

.hero-trial-text .check-icon {
    color: var(--color-primary);
    font-weight: bold;
}

.hero-trial-text .separator {
    color: var(--color-border);
}

/* Chat Interface Mockup */
.category-hero-visual {
    position: relative;
    perspective: 1000px;
}

.chat-interface-mockup {
    background: white;
    border-radius: 24px;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.15), 0 0 0 1px rgba(0,0,0,0.03);
    overflow: hidden;
    transform: rotateY(-5deg) rotateX(2deg);
    transition: transform 0.5s ease;
    max-width: 400px;
    margin: 0 auto;
}

.chat-interface-mockup:hover {
    transform: rotateY(0) rotateX(0);
}

.chat-header {
    padding: 16px 20px;
    background: #F8FAFC;
    border-bottom: 1px solid #E2E8F0;
    display: flex;
    align-items: center;
    gap: 12px;
}

.bot-avatar {
    width: 40px;
    height: 40px;
}

.bot-info {
    display: flex;
    flex-direction: column;
}

.bot-name {
    font-weight: 600;
    font-size: 15px;
    color: #1E293B;
}

.bot-status {
    font-size: 12px;
    color: #10B981;
}

.chat-messages {
    padding: 20px;
    height: 380px;
    background: white;
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.message {
    max-width: 85%;
    padding: 12px 16px;
    border-radius: 16px;
    font-size: 15px;
    line-height: 1.5;
}

.message.user {
    align-self: flex-end;
    background: #3B82F6;
    color: white;
    border-bottom-right-radius: 4px;
}

.message.bot {
    align-self: flex-start;
    background: #F1F5F9;
    color: #334155;
    border-bottom-left-radius: 4px;
}

.math-problem {
    font-family: monospace;
}

.math-block {
    display: block;
    background: rgba(255,255,255,0.2);
    padding: 8px;
    border-radius: 8px;
    margin-top: 8px;
    font-family: 'Courier New', monospace;
}

.math-result {
    font-family: 'Courier New', monospace;
    background: white;
    padding: 8px;
    border-radius: 8px;
    border: 1px solid #E2E8F0;
    margin: 8px 0;
}

.typing-dots {
    display: flex;
    gap: 4px;
}

.typing-dots span {
    width: 6px;
    height: 6px;
    background: #94A3B8;
    border-radius: 50%;
    animation: bounce 1.4s infinite ease-in-out both;
}

.typing-dots span:nth-child(1) { animation-delay: -0.32s; }
.typing-dots span:nth-child(2) { animation-delay: -0.16s; }

@keyframes bounce {
    0%, 80%, 100% { transform: scale(0); }
    40% { transform: scale(1); }
}

.chat-input-area {
    padding: 16px;
    border-top: 1px solid #E2E8F0;
    display: flex;
    align-items: center;
    gap: 12px;
}

.chat-input-placeholder {
    flex: 1;
    color: #94A3B8;
    font-size: 14px;
}

.chat-send-btn {
    width: 36px;
    height: 36px;
    background: #3B82F6;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
}

.chat-send-btn svg {
    width: 18px;
    height: 18px;
}

/* Trust Bar */
.trust-bar {
    background: white;
    border-bottom: 1px solid var(--color-border-light);
    padding: 40px 0;
}

.trust-grid {
    display: flex;
    justify-content: space-around;
    align-items: center;
    flex-wrap: wrap;
    gap: 32px;
}

.trust-item {
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.trust-number {
    font-size: 32px;
    font-weight: 800;
    color: var(--color-primary);
    line-height: 1;
    margin-bottom: 8px;
}

.trust-label {
    font-size: 14px;
    color: var(--color-text-light);
    font-weight: 500;
}

/* Problem/Solution */
.problem-solution {
    padding: 100px 0;
    background: #F8FAFC;
}

.comparison-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    max-width: 900px;
    margin: 60px auto 0;
}

.comparison-card {
    background: white;
    padding: 40px;
    border-radius: 24px;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
    border: 1px solid transparent;
}

.comparison-card.problem {
    border-color: #FECACA;
}

.comparison-card.solution {
    border-color: #BFDBFE;
    box-shadow: 0 20px 25px -5px rgba(59, 130, 246, 0.1);
    transform: scale(1.05);
    z-index: 1;
}

.comparison-card .feature-icon {
    width: 56px;
    height: 56px;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 0 24px;
}

.comparison-card .feature-icon svg {
    width: 26px;
    height: 26px;
}

.comparison-card.problem .feature-icon {
    background: #FEF2F2;
    color: #EF4444;
}

.comparison-card.solution .feature-icon {
    background: #EFF6FF;
    color: #3B82F6;
}

.comparison-card h3 {
    font-size: 20px;
    font-weight: 700;
    margin-bottom: 20px;
}

.comparison-card ul {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.comparison-card li {
    padding-left: 24px;
    position: relative;
    font-size: 15px;
    color: var(--color-text-secondary);
}

.problem li::before {
    content: '×';
    position: absolute;
    left: 0;
    color: #EF4444;
    font-weight: bold;
    font-size: 18px;
    line-height: 1;
}

.solution li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: #3B82F6;
    font-weight: bold;
}

/* Subject Features */
.subject-features {
    padding: 100px 0;
    background: white;
}

.features-grid-large {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 40px;
}

.feature-box {
    padding: 32px;
    border-radius: 20px;
    background: #FAFAFA;
    transition: transform 0.3s ease;
}

.feature-box:hover {
    transform: translateY(-5px);
    background: white;
    box-shadow: 0 10px 30px -5px rgba(0,0,0,0.05);
}

.feature-box-icon {
    width: 56px;
    height: 56px;
    border-radius: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 24px;
    color: white;
}

.color-1 { background: linear-gradient(135deg, #3B82F6, #2563EB); }
.color-2 { background: linear-gradient(135deg, #10B981, #059669); }
.color-3 { background: linear-gradient(135deg, #F59E0B, #D97706); }
.color-4 { background: linear-gradient(135deg, #8B5CF6, #7C3AED); }

.feature-box h3 {
    font-size: 20px;
    font-weight: 700;
    margin-bottom: 12px;
    color: var(--color-text);
}

.feature-box p {
    color: var(--color-text-light);
    line-height: 1.6;
}

/* How it works Alt */
.how-it-works-alt {
    padding: 100px 0;
    background: white;
}

.steps-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 900px;
    margin: 60px auto 0;
}

.step-col {
    text-align: center;
    flex: 1;
}

.step-num {
    width: 48px;
    height: 48px;
    background: #EFF6FF;
    color: #3B82F6;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 800;
    font-size: 20px;
    margin: 0 auto 24px;
}

.step-arrow {
    font-size: 24px;
    color: #CBD5E1;
    font-weight: 300;
    padding: 0 20px;
}

/* Subjects interlinking (category page) */
.subjects-interlinking {
    padding: 48px 0;
    background: var(--color-bg);
}

.subjects-interlinking-title {
    font-size: 18px;
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: 24px;
    text-align: center;
}

.subjects-interlinking .subjects-grid-compact {
    margin: 0;
}

.subject-card-compact.current {
    border-color: var(--color-primary-light);
    background: white;
}

.subject-card-compact.current .subject-card-title {
    color: var(--color-primary);
}

.subject-card-compact.current .subject-card-arrow {
    color: var(--color-primary);
}

/* Subject Content / SEO */
.subject-content {
    padding: 80px 0;
    background: #F8FAFC;
}

.content-wrapper-single {
    max-width: 800px;
    margin: 0 auto;
}

.seo-text-block {
    font-size: 16px;
    line-height: 1.8;
    color: var(--color-text-secondary);
}

/* Final CTA Redesigned - Stylish block on all pages */
.final-cta-redesigned {
    padding: 80px 0;
    background: linear-gradient(180deg, #F8FAFC 0%, #EEF2FF 100%);
}

.cta-box {
    background: linear-gradient(135deg, #3B82F6 0%, #6366F1 50%, #8B5CF6 100%);
    border-radius: 24px;
    padding: 56px 64px;
    text-align: center;
    color: white;
    max-width: 800px;
    margin: 0 auto;
    position: relative;
    overflow: hidden;
    box-shadow: 0 25px 50px -12px rgba(59, 130, 246, 0.35), 0 0 0 1px rgba(255,255,255,0.1) inset;
}

.cta-box::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -20%;
    width: 60%;
    height: 200%;
    background: radial-gradient(ellipse, rgba(255,255,255,0.15) 0%, transparent 70%);
    pointer-events: none;
}

.cta-text-content h2 {
    font-size: 32px;
    font-weight: 800;
    margin-bottom: 12px;
    color: white;
    letter-spacing: -0.02em;
}

.cta-text-content p {
    font-size: 17px;
    color: rgba(255, 255, 255, 0.95);
    margin-bottom: 28px;
    line-height: 1.6;
}

.btn-white {
    background: white;
    color: #3B82F6;
    box-shadow: 0 4px 14px rgba(0, 0, 0, 0.1);
}

.btn-white:hover {
    background: #F8FAFC;
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.15);
}

.pulse-animation {
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0% {
        box-shadow: 0 0 0 0 rgba(255, 255, 255, 0.4);
    }
    70% {
        box-shadow: 0 0 0 10px rgba(255, 255, 255, 0);
    }
    100% {
        box-shadow: 0 0 0 0 rgba(255, 255, 255, 0);
    }
}

.breadcrumbs-bottom {
    padding: 24px 0;
    background: white;
    border-top: 1px solid var(--color-border-light);
}

@media (max-width: 1024px) {
    .category-hero .container {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .category-hero-content {
        margin: 0 auto;
        align-items: center;
        display: flex;
        flex-direction: column;
    }
    
    .category-hero-actions {
        align-items: center;
    }
    
    .category-hero-visual {
        margin-top: 60px;
        max-width: 500px;
        margin-left: auto;
        margin-right: auto;
    }
}

/* ========================================
   Category Page - Mobile (must be last to override)
   ======================================== */
@media (max-width: 768px) {
    .breadcrumbs,
    .breadcrumbs-top {
        padding: 12px 0;
        margin-top: var(--header-height);
    }

    .category-hero {
        padding: 12px 0 32px !important;
    }

    .category-hero .container {
        gap: 24px;
    }

    .category-hero-content {
        max-width: 100%;
        align-items: center;
        text-align: center;
    }

    .category-badge {
        margin-bottom: 16px;
        font-size: 12px;
        padding: 6px 12px;
    }

    .category-hero-title {
        font-size: 28px !important;
        line-height: 1.2 !important;
        margin-bottom: 12px !important;
    }

    .category-hero-subtitle {
        font-size: 15px !important;
        margin-bottom: 20px !important;
    }

    .category-hero-actions {
        align-items: center;
        width: 100%;
    }

    .category-hero-actions .btn {
        width: 100%;
        justify-content: center;
    }

    .hero-trial-text {
        flex-wrap: wrap;
        justify-content: center;
        gap: 4px 12px;
    }

    .category-hero-visual {
        margin-top: 20px !important;
        max-width: 100%;
        width: 100%;
    }

    .chat-interface-mockup {
        max-width: 100% !important;
        transform: none !important;
        border-radius: 16px;
    }

    .chat-messages {
        height: auto !important;
        min-height: 200px;
        padding: 12px;
    }

    .message {
        font-size: 13px;
        padding: 10px 14px;
    }

    .trust-bar {
        padding: 24px 16px;
    }

    .trust-grid {
        display: grid !important;
        grid-template-columns: repeat(2, 1fr) !important;
        gap: 16px 12px !important;
        justify-content: stretch !important;
    }

    .trust-item {
        min-width: 0;
    }

    .trust-number {
        font-size: 20px !important;
    }

    .trust-label {
        font-size: 11px !important;
        line-height: 1.2;
    }

    .problem-solution {
        padding: 48px 0 !important;
    }

    .problem-solution .section-header {
        margin-bottom: 28px;
    }

    .problem-solution .section-title {
        font-size: 22px;
        margin-bottom: 12px;
    }

    .problem-solution .section-subtitle {
        font-size: 14px;
    }

    .comparison-grid {
        display: flex !important;
        flex-direction: column !important;
        gap: 16px !important;
        margin-top: 0 !important;
    }

    .comparison-card {
        width: 100% !important;
        max-width: 100% !important;
        padding: 20px !important;
        border-radius: 16px;
    }

    .comparison-card.solution {
        transform: none !important;
    }

    .subject-features {
        padding: 48px 0 !important;
    }

    .features-grid-large {
        display: flex !important;
        flex-direction: column !important;
        gap: 16px !important;
    }

    .feature-box {
        width: 100% !important;
        max-width: 100% !important;
        padding: 20px !important;
        border-radius: 16px;
    }

    .how-it-works-alt {
        padding: 48px 0 !important;
    }

    .how-it-works-alt .section-title {
        font-size: 22px;
        margin-bottom: 24px;
    }

    .steps-row {
        display: flex !important;
        flex-direction: column !important;
        gap: 24px !important;
        margin-top: 0 !important;
    }

    .step-arrow {
        display: none !important;
    }

    .step-col {
        padding: 16px;
        background: #F8FAFC;
        border-radius: 12px;
    }

    .subjects-interlinking {
        padding: 32px 0 !important;
    }

    .subjects-interlinking-title {
        font-size: 16px;
        margin-bottom: 16px;
    }

    .category-content {
        padding: 32px 0 !important;
    }

    .content-wrapper {
        gap: 24px !important;
    }

    .sidebar-card {
        padding: 20px !important;
    }

    .final-cta-redesigned {
        padding: 32px 0 !important;
    }

    .cta-box {
        padding: 32px 20px !important;
    }

    .cta-text-content h2 {
        font-size: 22px !important;
    }

    .cta-text-content p {
        font-size: 15px !important;
    }

    .container {
        padding: 0 16px;
    }
}