/* ========================================
   CS 224G - Advanced LLM Course Website
   Stanford University - Winter 2026
   ======================================== */

/* CSS Variables */
:root {
    /* Colors - Stanford Cardinal inspired with tech accents */
    --cardinal: #8C1515;
    --cardinal-dark: #6B0F0F;
    --cardinal-light: #B83A3A;
    
    --accent-1: #FF6B35;
    --accent-2: #00D4AA;
    --accent-3: #7C3AED;
    --accent-4: #3B82F6;
    
    --bg-dark: #0A0A0F;
    --bg-card: #12121A;
    --bg-card-hover: #1A1A24;
    --bg-elevated: #1E1E2A;
    
    --text-primary: #FAFAFA;
    --text-secondary: #A0A0B0;
    --text-muted: #606070;
    
    --border: rgba(255, 255, 255, 0.08);
    --border-hover: rgba(255, 255, 255, 0.15);
    
    /* Gradients */
    --gradient-primary: linear-gradient(135deg, var(--cardinal) 0%, var(--accent-1) 100%);
    --gradient-accent: linear-gradient(135deg, var(--accent-3) 0%, var(--accent-4) 100%);
    --gradient-glow: radial-gradient(circle, rgba(140, 21, 21, 0.15) 0%, transparent 70%);
    
    /* Typography */
    --font-display: 'Outfit', sans-serif;
    --font-mono: 'JetBrains Mono', monospace;
    
    /* Spacing */
    --section-padding: clamp(4rem, 10vw, 8rem);
    --container-max: 1200px;
    
    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-base: 0.3s ease;
    --transition-slow: 0.5s ease;
}

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

html {
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-display);
    background: var(--bg-dark);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
}

a {
    color: inherit;
    text-decoration: none;
}

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

/* Background Effects */
.bg-grid {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image: 
        linear-gradient(rgba(255,255,255,0.02) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255,255,255,0.02) 1px, transparent 1px);
    background-size: 60px 60px;
    pointer-events: none;
    z-index: -1;
}

.bg-glow {
    position: fixed;
    border-radius: 50%;
    filter: blur(120px);
    pointer-events: none;
    z-index: -1;
    opacity: 0.5;
}

.bg-glow-1 {
    width: 600px;
    height: 600px;
    background: var(--cardinal);
    top: -200px;
    right: -200px;
    animation: float 20s ease-in-out infinite;
}

.bg-glow-2 {
    width: 400px;
    height: 400px;
    background: var(--accent-3);
    bottom: 20%;
    left: -100px;
    animation: float 25s ease-in-out infinite reverse;
}

.bg-glow-3 {
    width: 500px;
    height: 500px;
    background: var(--accent-4);
    bottom: -200px;
    right: 20%;
    animation: float 30s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translate(0, 0) scale(1); }
    25% { transform: translate(30px, -30px) scale(1.05); }
    50% { transform: translate(-20px, 20px) scale(0.95); }
    75% { transform: translate(20px, 10px) scale(1.02); }
}

/* Container */
.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 2rem;
}

/* Navigation */
.main-nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    padding: 1rem 2rem;
    background: rgba(10, 10, 15, 0.8);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border);
}

.nav-container {
    max-width: var(--container-max);
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.logo-text {
    font-size: 1.5rem;
    font-weight: 700;
    letter-spacing: -0.02em;
}

.logo-badge {
    font-size: 0.75rem;
    font-weight: 600;
    padding: 0.25rem 0.5rem;
    background: var(--gradient-primary);
    border-radius: 4px;
}

.nav-links {
    display: flex;
    gap: 0.5rem;
}

.nav-link {
    padding: 0.5rem 1rem;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-secondary);
    border-radius: 8px;
    transition: all var(--transition-fast);
}

.nav-link:hover,
.nav-link.active {
    color: var(--text-primary);
    background: rgba(255, 255, 255, 0.05);
}

.nav-cta {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.6rem 1.25rem;
    font-size: 0.9rem;
    font-weight: 600;
    background: var(--gradient-primary);
    border-radius: 8px;
    transition: all var(--transition-base);
}

.nav-cta:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 30px rgba(140, 21, 21, 0.3);
}

/* Hero Section */
.hero {
    min-height: 100vh;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
    padding: calc(80px + var(--section-padding)) 2rem var(--section-padding);
    max-width: var(--container-max);
    margin: 0 auto;
}

.hero-content {
    animation: fadeInUp 0.8s ease-out;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.5rem 1rem;
    background: rgba(140, 21, 21, 0.15);
    border: 1px solid rgba(140, 21, 21, 0.3);
    border-radius: 100px;
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--cardinal-light);
    margin-bottom: 1.5rem;
}

.pulse {
    width: 8px;
    height: 8px;
    background: var(--accent-2);
    border-radius: 50%;
    animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { opacity: 1; transform: scale(1); }
    50% { opacity: 0.5; transform: scale(1.2); }
}

.hero-title {
    font-size: clamp(2.5rem, 5vw, 4rem);
    font-weight: 800;
    line-height: 1.1;
    letter-spacing: -0.03em;
    margin-bottom: 1.5rem;
}

.title-line {
    display: block;
}

.gradient-text {
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.1rem;
    color: var(--text-secondary);
    max-width: 500px;
    margin-bottom: 2rem;
    line-height: 1.7;
}

.hero-stats {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    margin-bottom: 2.5rem;
    padding: 1.25rem 1.5rem;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 12px;
}

.stat {
    text-align: center;
}

.stat-number {
    display: block;
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--text-primary);
    font-family: var(--font-mono);
}

.stat-label {
    font-size: 0.8rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.stat-divider {
    width: 1px;
    height: 40px;
    background: var(--border);
}

.hero-actions {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.875rem 1.5rem;
    font-size: 0.95rem;
    font-weight: 600;
    border-radius: 10px;
    transition: all var(--transition-base);
    cursor: pointer;
    border: none;
}

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 15px 40px rgba(140, 21, 21, 0.4);
}

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

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

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

.btn-ghost:hover {
    background: rgba(255, 255, 255, 0.05);
    color: var(--text-primary);
    border-color: var(--border-hover);
}

/* Hero Visual - Code Window */
.hero-visual {
    animation: fadeInUp 0.8s ease-out 0.2s both;
}

.code-window {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 16px;
    overflow: hidden;
    box-shadow: 
        0 50px 100px rgba(0, 0, 0, 0.5),
        0 0 0 1px rgba(255, 255, 255, 0.05) inset;
}

.code-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem 1.25rem;
    background: rgba(255, 255, 255, 0.02);
    border-bottom: 1px solid var(--border);
}

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

.code-dots span {
    width: 12px;
    height: 12px;
    border-radius: 50%;
}

.code-dots span:nth-child(1) { background: #FF5F57; }
.code-dots span:nth-child(2) { background: #FFBD2E; }
.code-dots span:nth-child(3) { background: #28CA41; }

.code-title {
    font-family: var(--font-mono);
    font-size: 0.8rem;
    color: var(--text-muted);
}

.code-content {
    padding: 1.5rem;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    line-height: 1.8;
    overflow-x: auto;
}

.code-keyword { color: #FF79C6; }
.code-module { color: #8BE9FD; }
.code-class { color: #50FA7B; }
.code-function { color: #FFB86C; }
.code-string { color: #F1FA8C; }
.code-comment { color: #6272A4; }

.cursor {
    animation: blink 1s step-end infinite;
}

@keyframes blink {
    0%, 100% { opacity: 1; }
    50% { opacity: 0; }
}

/* Info Section */
.info-section {
    padding: var(--section-padding) 0;
    margin-top: -4rem;
}

.info-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1.5rem;
}

.info-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 1.5rem;
    transition: all var(--transition-base);
}

.info-card:hover {
    background: var(--bg-card-hover);
    border-color: var(--border-hover);
    transform: translateY(-4px);
}

.info-card.primary-card {
    background: var(--gradient-primary);
    border: none;
}

.info-card.primary-card .card-detail,
.info-card.primary-card .card-highlight {
    color: rgba(255, 255, 255, 0.9);
}

.card-icon {
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 12px;
    margin-bottom: 1rem;
}

.card-content h3 {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 0.5rem;
}

.card-detail {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.card-highlight {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
}

/* Section Headers */
.section-header {
    margin-bottom: 3rem;
}

.section-header.centered {
    text-align: center;
}

.section-tag {
    display: inline-block;
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--cardinal-light);
    margin-bottom: 0.75rem;
}

.section-title {
    font-size: clamp(1.75rem, 4vw, 2.5rem);
    font-weight: 700;
    letter-spacing: -0.02em;
}

/* About Section */
.about-section {
    padding: var(--section-padding) 0;
}

.about-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
}

.about-text .lead {
    font-size: 1.25rem;
    font-weight: 500;
    color: var(--text-primary);
    line-height: 1.6;
    margin-bottom: 1.5rem;
}

.about-text p {
    color: var(--text-secondary);
    margin-bottom: 1.25rem;
}

.about-topics h4 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

.topics-grid {
    display: grid;
    gap: 0.75rem;
}

.topic-item {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem 1.25rem;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 10px;
    font-size: 0.95rem;
    color: var(--text-secondary);
    transition: all var(--transition-fast);
}

.topic-item:hover {
    background: var(--bg-card-hover);
    border-color: var(--border-hover);
    color: var(--text-primary);
}

.topic-icon {
    font-size: 1.25rem;
}

/* Instructors Section */
.instructors-section {
    padding: var(--section-padding) 0;
    background: var(--bg-card);
}

.instructors-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
    margin-bottom: 3rem;
}

.instructor-card {
    background: var(--bg-elevated);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 2rem;
    text-align: center;
    transition: all var(--transition-base);
}

.instructor-card:hover {
    transform: translateY(-4px);
    border-color: var(--border-hover);
}

.instructor-image {
    margin-bottom: 1.5rem;
    display: flex;
    justify-content: center;
}

.instructor-image img {
    width: 100px;
    height: 100px;
    object-fit: cover;
    border-radius: 50%;
    border: 2px solid var(--border);
}

.image-placeholder {
    width: 100px;
    height: 100px;
    margin: 0 auto;
    background: var(--gradient-primary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    font-weight: 700;
}

.instructor-info h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.instructor-title {
    font-size: 0.9rem;
    color: var(--cardinal-light);
    margin-bottom: 0.75rem;
}

.instructor-bio {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.instructor-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.85rem;
    color: var(--accent-4);
    transition: all var(--transition-fast);
}

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

/* Instructor grid for 2 instructors */
.instructors-grid-2 {
    grid-template-columns: repeat(2, 1fr);
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

/* Course Assistants */
.course-assistants {
    margin-top: 2rem;
    margin-bottom: 3rem;
}

.course-assistants h4 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    text-align: center;
    margin-bottom: 1.5rem;
}

.assistants-grid {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
    flex-wrap: wrap;
}

.assistant-card {
    display: flex;
    align-items: center;
    gap: 1rem;
    background: var(--bg-elevated);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 1rem 1.5rem;
    transition: all var(--transition-base);
}

.assistant-card:hover {
    border-color: var(--border-hover);
}

.assistant-image img,
.assistant-image .image-placeholder {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    object-fit: cover;
    border: 1px solid var(--border);
}

.assistant-image .image-placeholder {
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--gradient-primary);
    font-size: 0.9rem;
    font-weight: 600;
    border: none;
}

.assistant-info h5 {
    font-size: 0.95rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.assistant-email {
    display: block;
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-bottom: 0.25rem;
    transition: color var(--transition-fast);
}

.assistant-email:hover {
    color: var(--accent-4);
}

.assistant-link {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    font-size: 0.75rem;
    color: var(--accent-4);
    transition: color var(--transition-fast);
}

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

.office-hours {
    background: var(--bg-elevated);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 2rem;
}

.office-hours h4 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    text-align: center;
}

.office-hours-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1.5rem;
}

.oh-item {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
    padding: 1rem;
    background: var(--bg-card);
    border-radius: 10px;
}

.oh-person {
    font-weight: 600;
    color: var(--text-primary);
}

.oh-time {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.oh-location {
    font-size: 0.85rem;
    color: var(--text-muted);
}

/* Prerequisites Section */
.prereq-section {
    padding: var(--section-padding) 0;
}

.prereq-content {
    display: grid;
    grid-template-columns: 1.5fr 1fr;
    gap: 3rem;
}

.prereq-list {
    display: grid;
    gap: 1rem;
}

.prereq-item {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 1.25rem 1.5rem;
    transition: all var(--transition-fast);
}

.prereq-item:hover {
    border-color: var(--border-hover);
}

.prereq-badge {
    display: inline-block;
    font-size: 0.7rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    margin-bottom: 0.5rem;
}

.prereq-item.required .prereq-badge {
    background: rgba(140, 21, 21, 0.2);
    color: var(--cardinal-light);
}

.prereq-item.recommended .prereq-badge {
    background: rgba(0, 212, 170, 0.2);
    color: var(--accent-2);
}

.prereq-item h4 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.prereq-item p {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.prereq-note {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 2rem;
    height: fit-content;
}

.note-icon {
    font-size: 2rem;
    margin-bottom: 1rem;
}

.prereq-note h4 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
}

.prereq-note p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

.prereq-note a {
    color: var(--accent-4);
    text-decoration: underline;
}

/* Grading Section */
.grading-section {
    padding: var(--section-padding) 0;
    background: var(--bg-card);
}

.grading-visual {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6rem;
}

.grade-ring {
    position: relative;
    width: 280px;
    height: 280px;
}

.ring-svg {
    width: 100%;
    height: 100%;
    transform: rotate(-90deg);
}

.ring-bg {
    fill: none;
    stroke: var(--border);
    stroke-width: 20;
}

.ring-fill {
    fill: none;
    stroke-width: 20;
    stroke-linecap: round;
    stroke-dasharray: var(--dash) 502;
    stroke-dashoffset: var(--offset);
    transition: all 1s ease;
}

.ring-participation { stroke: var(--accent-2); }
.ring-sprints { stroke: var(--accent-3); }
.ring-final { stroke: var(--cardinal); }

.ring-center {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
}

.ring-total {
    font-size: 2rem;
    font-weight: 700;
    font-family: var(--font-mono);
}

.grade-legend {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.legend-item {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
}

.legend-color {
    width: 16px;
    height: 16px;
    border-radius: 4px;
    margin-top: 4px;
}

.legend-color.participation { background: var(--accent-2); }
.legend-color.sprints { background: var(--accent-3); }
.legend-color.final { background: var(--cardinal); }

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

.legend-percent {
    font-size: 1.5rem;
    font-weight: 700;
    font-family: var(--font-mono);
}

.legend-label {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
}

.legend-desc {
    font-size: 0.85rem;
    color: var(--text-muted);
}

/* Logistics Section */
.logistics-section {
    padding: var(--section-padding) 0;
}

.logistics-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1.5rem;
}

.logistics-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 1.5rem;
    transition: all var(--transition-fast);
}

.logistics-card:hover {
    border-color: var(--border-hover);
}

.logistics-card h4 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
}

.logistics-card p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

.logistics-card a {
    color: var(--accent-4);
}

.logistics-card strong {
    color: var(--text-primary);
}

/* Enrollment Section */
.enrollment-section {
    padding: var(--section-padding) 0;
}

.enrollment-card {
    display: grid;
    grid-template-columns: 1fr 1fr;
    align-items: center;
    gap: 4rem;
    background: var(--gradient-primary);
    border-radius: 24px;
    padding: 4rem;
    overflow: hidden;
    position: relative;
}

.enrollment-content h2 {
    font-size: clamp(1.5rem, 3vw, 2rem);
    font-weight: 700;
    margin-bottom: 1rem;
}

.enrollment-content p {
    font-size: 1rem;
    opacity: 0.9;
    margin-bottom: 2rem;
    line-height: 1.6;
}

.enrollment-actions {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.enrollment-card .btn-primary {
    background: white;
    color: var(--cardinal);
}

.enrollment-card .btn-primary:hover {
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.3);
}

.enrollment-card .btn-ghost {
    border-color: rgba(255, 255, 255, 0.3);
    color: white;
}

.enrollment-card .btn-ghost:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: rgba(255, 255, 255, 0.5);
}

.enrollment-visual {
    display: flex;
    justify-content: center;
    align-items: center;
}

.visual-orbit {
    position: relative;
    width: 200px;
    height: 200px;
}

.orbit-ring {
    position: absolute;
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 50%;
    animation: spin 20s linear infinite;
}

.orbit-ring:nth-child(1) {
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
}

.orbit-ring:nth-child(2) {
    width: 70%;
    height: 70%;
    top: 15%;
    left: 15%;
    animation-duration: 15s;
    animation-direction: reverse;
}

.orbit-ring:nth-child(3) {
    width: 40%;
    height: 40%;
    top: 30%;
    left: 30%;
    animation-duration: 10s;
}

@keyframes spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

.orbit-dot {
    position: absolute;
    width: 12px;
    height: 12px;
    background: white;
    border-radius: 50%;
    animation: orbit 10s linear infinite;
}

.dot-1 {
    top: 0;
    left: 50%;
    transform: translateX(-50%);
}

.dot-2 {
    top: 50%;
    left: 0;
    transform: translateY(-50%);
    animation-delay: -3.33s;
}

.dot-3 {
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    animation-delay: -6.66s;
}

/* Footer */
.main-footer {
    padding: 4rem 0 2rem;
    background: var(--bg-card);
    border-top: 1px solid var(--border);
}

.footer-content {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 4rem;
    margin-bottom: 3rem;
}

.footer-brand {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.footer-logo {
    font-size: 1.5rem;
    font-weight: 700;
}

.footer-brand p {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.footer-stanford {
    color: var(--text-muted);
    font-size: 0.85rem;
}

.footer-links {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
}

.footer-col h5 {
    font-size: 0.85rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 1rem;
    color: var(--text-muted);
}

.footer-col a {
    display: block;
    font-size: 0.9rem;
    color: var(--text-secondary);
    padding: 0.35rem 0;
    transition: color var(--transition-fast);
}

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

.footer-bottom {
    padding-top: 2rem;
    border-top: 1px solid var(--border);
    text-align: center;
}

.footer-bottom p {
    font-size: 0.85rem;
    color: var(--text-muted);
}

/* Responsive Design */
@media (max-width: 1024px) {
    .hero {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-subtitle {
        margin: 0 auto 2rem;
    }
    
    .hero-stats {
        justify-content: center;
    }
    
    .hero-actions {
        justify-content: center;
    }
    
    .hero-visual {
        max-width: 500px;
        margin: 0 auto;
    }
    
    .info-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .about-content {
        grid-template-columns: 1fr;
    }
    
    .instructors-grid,
    .instructors-grid-2 {
        grid-template-columns: 1fr;
        max-width: none;
    }

    .assistants-grid {
        flex-direction: column;
        align-items: center;
    }
    
    .prereq-content {
        grid-template-columns: 1fr;
    }
    
    .grading-visual {
        flex-direction: column;
        gap: 3rem;
    }
    
    .enrollment-card {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .enrollment-actions {
        justify-content: center;
    }
    
    .enrollment-visual {
        display: none;
    }
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
    }
    
    .info-grid {
        grid-template-columns: 1fr;
    }
    
    .hero-stats {
        flex-wrap: wrap;
        justify-content: center;
    }
    
    .stat-divider {
        display: none;
    }
    
    .logistics-grid {
        grid-template-columns: 1fr;
    }
    
    .office-hours-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
    }
    
    .footer-links {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 1rem;
    }
    
    .hero {
        padding-left: 1rem;
        padding-right: 1rem;
    }
    
    .enrollment-card {
        padding: 2rem;
    }
    
    .footer-links {
        grid-template-columns: 1fr;
    }
}