/* ============================================
   StudentAI Premium Landing Page
   Colors from source: #0e0c1a (bg), #f1f1f1 (fg), #8858f0 (primary)
   Typography: Inter (Google Fonts)
   ============================================ */

:root {
    --bg-dark: #0e0c1a;
    --fg-light: #f1f1f1;
    --bg-light: #f8f8f8;
    --text-dark: #080810;
    --primary: #8858f0;
    --primary-light: #a098f8;
    --accent: #a0f0d0;
    --border-color: #d0d0d8;
    --surface: #080818;
    --gray-medium: #98a0a8;
    --gray-dark: #101820;

    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 40px;
    --spacing-2xl: 80px;

    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-weight-regular: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;
    --font-weight-black: 900;

    --transition: all 0.3s ease;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    background-color: var(--bg-dark);
    color: var(--fg-light);
    line-height: 1.6;
    font-weight: var(--font-weight-regular);
}

/* ============================================
   Typography
   ============================================ */

h1, h2, h3, h4, h5, h6 {
    font-weight: var(--font-weight-bold);
    line-height: 1.2;
}

h1 {
    font-size: clamp(2rem, 5vw, 3.5rem);
    font-weight: var(--font-weight-black);
}

h2 {
    font-size: clamp(1.75rem, 4vw, 2.75rem);
    font-weight: var(--font-weight-black);
}

h3 {
    font-size: clamp(1.25rem, 2.5vw, 1.75rem);
}

h4 {
    font-size: 1.125rem;
}

h5 {
    font-size: 1rem;
}

p {
    font-size: 1rem;
    line-height: 1.8;
}

.section-subtitle {
    font-size: 1.125rem;
    color: var(--gray-medium);
    margin-top: var(--spacing-md);
}

/* ============================================
   Layout & Containers
   ============================================ */

.section-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

section {
    padding: var(--spacing-2xl) 0;
}

@media (max-width: 768px) {
    section {
        padding: var(--spacing-xl) 0;
    }

    .section-container {
        padding: 0 var(--spacing-md);
    }
}

/* ============================================
   Navigation Bar
   ============================================ */

.navbar {
    position: sticky;
    top: 0;
    z-index: 100;
    background-color: rgba(14, 12, 26, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid rgba(208, 208, 216, 0.1);
    padding: var(--spacing-md) 0;
}

.navbar-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: var(--spacing-lg);
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    text-decoration: none;
    color: var(--fg-light);
    font-weight: var(--font-weight-bold);
    font-size: 1.25rem;
}

.logo-img {
    width: 32px;
    height: 32px;
    object-fit: contain;
}

.logo-text {
    font-weight: var(--font-weight-black);
    background: linear-gradient(135deg, var(--primary) 0%, var(--accent) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-menu {
    display: flex;
    gap: var(--spacing-xl);
    flex: 1;
}

.nav-link {
    color: var(--fg-light);
    text-decoration: none;
    font-weight: var(--font-weight-medium);
    transition: var(--transition);
    position: relative;
}

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

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--primary);
    transition: width 0.3s ease;
}

.nav-link:hover::after {
    width: 100%;
}

.nav-actions {
    display: flex;
    gap: var(--spacing-md);
    align-items: center;
}

.btn-link {
    color: var(--fg-light);
    text-decoration: none;
    transition: var(--transition);
}

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

@media (max-width: 768px) {
    .nav-menu {
        display: none;
    }

    .navbar-container {
        gap: var(--spacing-md);
    }
}

/* ============================================
   Buttons
   ============================================ */

.btn-primary-sm,
.btn-primary-large,
.btn-secondary,
.btn-secondary-large {
    display: inline-block;
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: 8px;
    text-decoration: none;
    font-weight: var(--font-weight-semibold);
    transition: var(--transition);
    border: none;
    cursor: pointer;
    font-family: var(--font-family);
    font-size: 1rem;
    text-align: center;
    min-height: 48px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
}

.btn-primary-sm {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
    color: var(--bg-dark);
    padding: 8px 16px;
    font-size: 0.9rem;
}

.btn-primary-sm:hover {
    opacity: 0.9;
    transform: translateY(-2px);
    box-shadow: 0 8px 16px rgba(136, 88, 240, 0.3);
}

.btn-primary-large {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
    color: var(--bg-dark);
    padding: var(--spacing-lg) var(--spacing-2xl);
    font-size: 1.125rem;
    font-weight: var(--font-weight-bold);
}

.btn-primary-large:hover {
    opacity: 0.9;
    transform: translateY(-2px);
    box-shadow: 0 12px 24px rgba(136, 88, 240, 0.4);
}

.btn-secondary {
    background-color: transparent;
    color: var(--fg-light);
    border: 2px solid var(--primary);
    padding: calc(var(--spacing-md) - 2px) calc(var(--spacing-lg) - 2px);
}

.btn-secondary:hover {
    background-color: rgba(136, 88, 240, 0.1);
    color: var(--primary);
}

.btn-secondary-large {
    background-color: transparent;
    color: var(--fg-light);
    border: 2px solid var(--primary);
    padding: calc(var(--spacing-lg) - 2px) calc(var(--spacing-2xl) - 2px);
    font-size: 1.125rem;
}

.btn-secondary-large:hover {
    background-color: rgba(136, 88, 240, 0.1);
    color: var(--primary);
}

/* ============================================
   Hero Section
   ============================================ */

.hero {
    position: relative;
    padding: 120px var(--spacing-md) 80px;
    overflow: hidden;
    min-height: 100vh;
    display: flex;
    align-items: center;
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
    z-index: 0;
    opacity: 0.6;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(180deg, rgba(14, 12, 26, 0.8) 0%, rgba(8, 8, 16, 0.9) 100%);
    z-index: 1;
}

.hero-content {
    position: relative;
    z-index: 2;
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
}

.hero-title {
    margin-bottom: var(--spacing-lg);
    background: linear-gradient(135deg, var(--fg-light) 0%, var(--primary-light) 50%, var(--accent) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    line-height: 1.1;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--gray-medium);
    margin-bottom: var(--spacing-lg);
    line-height: 1.8;
}

.hero-trust {
    display: flex;
    justify-content: center;
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
    flex-wrap: wrap;
}

.trust-badge {
    display: inline-block;
    padding: var(--spacing-md) var(--spacing-lg);
    background-color: rgba(136, 88, 240, 0.1);
    border: 1px solid rgba(136, 88, 240, 0.3);
    border-radius: 24px;
    font-size: 0.9rem;
    color: var(--accent);
}

.hero-cta {
    display: flex;
    justify-content: center;
    gap: var(--spacing-lg);
    flex-wrap: wrap;
}

@media (max-width: 768px) {
    .hero {
        padding: 80px var(--spacing-md) 60px;
        min-height: auto;
    }

    .hero-title {
        font-size: 2rem;
    }

    .hero-subtitle {
        font-size: 1rem;
    }

    .hero-trust {
        gap: var(--spacing-md);
    }

    .trust-badge {
        padding: var(--spacing-md) var(--spacing-lg);
        font-size: 0.85rem;
    }

    .hero-cta {
        gap: var(--spacing-md);
    }
}

/* ============================================
   Value Props Section
   ============================================ */

.value-props {
    background-color: var(--surface);
}

.section-title {
    text-align: center;
    margin-bottom: var(--spacing-lg);
}

.props-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-lg);
    margin-top: var(--spacing-2xl);
}

.prop-card {
    background: linear-gradient(135deg, rgba(136, 88, 240, 0.05) 0%, rgba(160, 240, 208, 0.05) 100%);
    border: 1px solid rgba(136, 88, 240, 0.2);
    border-radius: 16px;
    padding: var(--spacing-xl);
    text-align: center;
    transition: var(--transition);
}

.prop-card:hover {
    border-color: var(--primary);
    background: linear-gradient(135deg, rgba(136, 88, 240, 0.1) 0%, rgba(160, 240, 208, 0.1) 100%);
    transform: translateY(-4px);
}

.prop-icon {
    width: 64px;
    height: 64px;
    margin: 0 auto var(--spacing-lg);
    color: var(--primary);
    display: flex;
    align-items: center;
    justify-content: center;
}

.prop-icon svg {
    width: 100%;
    height: 100%;
}

.prop-title {
    margin-bottom: var(--spacing-md);
    font-size: 1.25rem;
}

.prop-desc {
    color: var(--gray-medium);
    font-size: 0.95rem;
}

/* ============================================
   How It Works Section
   ============================================ */

.how-it-works {
    background-color: var(--bg-light);
    color: var(--text-dark);
}

.how-it-works .section-title,
.how-it-works .section-subtitle {
    color: var(--text-dark);
}

.how-it-works .section-subtitle {
    color: var(--gray-medium);
}

.steps-flow {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: var(--spacing-lg);
    flex-wrap: wrap;
    margin: var(--spacing-2xl) 0;
}

.step {
    flex: 1;
    min-width: 200px;
    text-align: center;
    background-color: white;
    padding: var(--spacing-xl);
    border-radius: 12px;
    border: 1px solid var(--border-color);
}

.step-number {
    width: 48px;
    height: 48px;
    margin: 0 auto var(--spacing-lg);
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: var(--font-weight-black);
    font-size: 1.5rem;
}

.step-title {
    margin-bottom: var(--spacing-md);
}

.step-desc {
    color: var(--gray-medium);
    font-size: 0.95rem;
}

.step-arrow {
    font-size: 1.5rem;
    color: var(--primary);
    font-weight: var(--font-weight-bold);
}

@media (max-width: 768px) {
    .steps-flow {
        flex-direction: column;
    }

    .step-arrow {
        transform: rotate(90deg);
    }
}

.product-showcase {
    margin-top: var(--spacing-2xl);
    text-align: center;
}

.showcase-image {
    max-width: 100%;
    height: auto;
    border-radius: 12px;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
}

/* ============================================
   Features Detailed Section
   ============================================ */

.features-detailed {
    background-color: var(--surface);
}

.features-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-xl);
    margin-top: var(--spacing-2xl);
}

.feature-item {
    background: rgba(136, 88, 240, 0.05);
    border: 1px solid rgba(136, 88, 240, 0.2);
    border-radius: 12px;
    padding: var(--spacing-xl);
    text-align: center;
    transition: var(--transition);
}

.feature-item:hover {
    border-color: var(--primary);
    background: rgba(136, 88, 240, 0.1);
    transform: translateY(-4px);
}

.feature-number {
    font-size: 3rem;
    margin-bottom: var(--spacing-md);
}

.feature-item h3 {
    margin-bottom: var(--spacing-md);
}

.feature-item p {
    color: var(--gray-medium);
    font-size: 0.95rem;
}

/* ============================================
   Testimonials Section
   ============================================ */

.testimonials {
    background-color: var(--bg-light);
    color: var(--text-dark);
}

.testimonials .section-title,
.testimonials .section-subtitle {
    color: var(--text-dark);
}

.testimonials .section-subtitle {
    color: var(--gray-medium);
}

.testimonials-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-xl);
    margin-top: var(--spacing-2xl);
}

.testimonial-card {
    background-color: white;
    border-radius: 12px;
    padding: var(--spacing-xl);
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

.testimonial-card:hover {
    box-shadow: 0 12px 24px rgba(0, 0, 0, 0.1);
    transform: translateY(-4px);
}

.testimonial-rating {
    margin-bottom: var(--spacing-lg);
}

.star {
    margin-right: 2px;
    font-size: 1.1rem;
}

.testimonial-quote {
    color: var(--text-dark);
    font-size: 1rem;
    line-height: 1.8;
    margin-bottom: var(--spacing-lg);
    font-style: italic;
}

.testimonial-author {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.author-photo {
    width: 48px;
    height: 48px;
    border-radius: 50%;
    object-fit: cover;
}

.author-info {
    text-align: left;
}

.author-name {
    font-size: 0.95rem;
    margin-bottom: 2px;
    color: var(--text-dark);
}

.author-detail {
    font-size: 0.85rem;
    color: var(--gray-medium);
}

/* ============================================
   FAQ Section
   ============================================ */

.faq {
    background-color: var(--surface);
}

.faq-items {
    max-width: 700px;
    margin: var(--spacing-2xl) auto 0;
}

.faq-item {
    margin-bottom: var(--spacing-lg);
    border: 1px solid rgba(136, 88, 240, 0.2);
    border-radius: 8px;
    overflow: hidden;
}

.faq-question {
    width: 100%;
    padding: var(--spacing-xl);
    background-color: rgba(136, 88, 240, 0.05);
    border: none;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    text-align: left;
    font-family: var(--font-family);
    font-weight: var(--font-weight-semibold);
    color: var(--fg-light);
    transition: var(--transition);
    font-size: 1rem;
}

.faq-question:hover {
    background-color: rgba(136, 88, 240, 0.1);
}

.faq-toggle {
    font-size: 1.5rem;
    transition: transform 0.3s ease;
    flex-shrink: 0;
    margin-left: var(--spacing-md);
}

.faq-question.active .faq-toggle {
    transform: rotate(45deg);
}

.faq-answer {
    display: none;
    padding: var(--spacing-xl);
    background-color: rgba(8, 8, 24, 0.5);
    color: var(--gray-medium);
    border-top: 1px solid rgba(136, 88, 240, 0.2);
    font-size: 0.95rem;
    line-height: 1.8;
}

.faq-answer.active {
    display: block;
}

/* ============================================
   Final CTA Section
   ============================================ */

.final-cta {
    background: linear-gradient(135deg, var(--surface) 0%, rgba(136, 88, 240, 0.1) 100%);
    text-align: center;
}

.cta-title {
    margin-bottom: var(--spacing-lg);
}

.cta-subtitle {
    color: var(--gray-medium);
    margin-bottom: var(--spacing-xl);
}

.cta-buttons {
    display: flex;
    justify-content: center;
    gap: var(--spacing-lg);
    flex-wrap: wrap;
    margin-bottom: var(--spacing-xl);
}

.cta-footer {
    color: var(--gray-medium);
    font-size: 0.9rem;
}

@media (max-width: 768px) {
    .cta-buttons {
        flex-direction: column;
    }

    .cta-buttons a {
        width: 100%;
    }
}

/* ============================================
   Footer
   ============================================ */

.footer {
    background-color: var(--surface);
    border-top: 1px solid rgba(208, 208, 216, 0.1);
    padding: var(--spacing-2xl) 0;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-2xl);
}

.footer-col {
    padding: 0 var(--spacing-md);
}

.footer-col h4,
.footer-col h5 {
    margin-bottom: var(--spacing-md);
    color: var(--fg-light);
    font-size: 1rem;
}

.footer-col p {
    color: var(--gray-medium);
    font-size: 0.9rem;
}

.footer-col ul {
    list-style: none;
}

.footer-col ul li {
    margin-bottom: var(--spacing-md);
}

.footer-col a {
    color: var(--gray-medium);
    text-decoration: none;
    font-size: 0.9rem;
    transition: var(--transition);
}

.footer-col a:hover {
    color: var(--primary);
}

.footer-bottom {
    text-align: center;
    padding-top: var(--spacing-xl);
    border-top: 1px solid rgba(208, 208, 216, 0.1);
    color: var(--gray-medium);
    font-size: 0.85rem;
}

/* ============================================
   Animations & Utilities
   ============================================ */

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

.fade-in-up {
    animation: fadeInUp 0.6s ease-out;
}

/* Smooth scroll behavior for mobile */
@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Mobile optimizations */
@media (max-width: 480px) {
    :root {
        --spacing-2xl: 40px;
    }

    .navbar-container {
        flex-direction: column;
        gap: var(--spacing-sm);
    }

    .nav-actions {
        width: 100%;
        gap: var(--spacing-sm);
    }

    .btn-primary-large,
    .btn-secondary-large {
        width: 100%;
    }

    .steps-flow {
        gap: var(--spacing-md);
    }

    .testimonials-grid {
        grid-template-columns: 1fr;
    }
}