/* Copyright (c) Meta Platforms, Inc. and affiliates.*/
/* This source code is licensed under the CC BY-NC 4.0 license found in the*/
/* LICENSE file in the root directory of this source tree.*/

/* ===== CSS Variables ===== */
:root {
    --color-bg-black: #ffffff;
    --color-bg-primary: #ffffff;
    --color-bg-secondary: #f5f5f7;
    --color-bg-tertiary: #e8e8ed;
    --color-bg-card: #f9f9fb;
    --color-text-primary: #1a1a2e;
    --color-text-secondary: #555566;
    --color-text-muted: #888899;
    --color-accent: #4f46e5;
    --color-accent-hover: #6366f1;
    --color-accent-light: rgba(79, 70, 229, 0.08);
    --color-border: #d8d8e0;
    --color-success: #10b981;
    --color-warning: #f59e0b;

    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 2rem;
    --font-size-4xl: 2.5rem;
    --font-size-5xl: 3.5rem;

    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    --spacing-4xl: 6rem;

    --border-radius-sm: 0.375rem;
    --border-radius-md: 0.5rem;
    --border-radius-lg: 0.75rem;
    --border-radius-xl: 1rem;
    --border-radius-full: 9999px;

    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.5);
    --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.6);

    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 350ms ease;

    --container-max-width: 1200px;
}

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

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

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--color-text-primary);
    background-color: var(--color-bg-primary);
    min-height: 100vh;
}

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

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

ul, ol {
    list-style: none;
}

button {
    font-family: inherit;
    cursor: pointer;
    border: none;
    background: none;
}

/* ===== Utility Classes ===== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: var(--font-size-sm);
    font-weight: 500;
    border-radius: var(--border-radius-md);
    transition: all var(--transition-fast);
    white-space: nowrap;
}

.btn-primary {
    background: var(--color-accent);
    color: var(--color-text-primary);
}

.btn-primary:hover {
    background: var(--color-accent-hover);
    transform: translateY(-1px);
}

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

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

/* ===== Hero Section ===== */
.hero {
    padding-top: var(--spacing-4xl);
    padding-bottom: var(--spacing-4xl);
    background: linear-gradient(180deg, var(--color-bg-primary) 0%, var(--color-bg-secondary) 100%);
}

.hero-container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
    text-align: center;
}

.hero-title {
    font-size: var(--font-size-4xl);
    font-weight: 700;
    line-height: 1.1;
    margin-bottom: var(--spacing-lg);
    background: linear-gradient(135deg, var(--color-text-primary) 0%, var(--color-accent) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

@media (min-width: 768px) {
    .hero-title {
        font-size: var(--font-size-5xl);
    }
}

.hero-subtitle {
    font-size: var(--font-size-xl);
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-lg);
    max-width: 1200px;
}

.hero-authors {
    margin-bottom: var(--spacing-xl);
    max-width: 1200px;
}

.author-list {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    line-height: 1.6;
    margin-bottom: var(--spacing-xs);
}

.author-affiliation {
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
    font-style: italic;
}

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

.hero-banner {
    max-width: var(--container-max-width);
    margin: var(--spacing-3xl) auto 0;
    padding: 0 var(--spacing-lg);
    border-radius: var(--border-radius-lg);
    overflow: hidden;
}

.hero-banner-caption {
    font-size: var(--font-size-xs);
    color: var(--color-text-muted);
    text-align: center;
    margin-top: var(--spacing-sm);
}

.hero-banner img,
.hero-banner video {
    width: 100%;
    max-height: 410px;
    object-fit: cover;
    display: block;
    border-radius: var(--border-radius-lg);
    border: 1px solid var(--color-border);
}

/* ===== Section Styles ===== */
.section-container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: var(--spacing-4xl) var(--spacing-lg);
}

.section-title {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    text-align: left;
    margin-bottom: var(--spacing-md);
}

.section-description {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    text-align: left;
    margin: 0 0 var(--spacing-3xl);
    max-width: none;
    line-height: 1.7;
}

/* ===== Full-Width Image ===== */
.full-width-image {
    width: 100%;
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    border: 1px solid var(--color-border);
}

.full-width-image img {
    width: 100%;
    height: auto;
    display: block;
}

/* ===== Purpose / Overview Section ===== */
.purpose-section {
    background: var(--color-bg-primary);
}

.purpose-grid {
    display: grid;
    gap: var(--spacing-xl);
}

@media (min-width: 768px) {
    .purpose-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

.video-card {
    background: var(--color-bg-card);
    border-radius: var(--border-radius-lg);
    border: 1px solid var(--color-border);
    overflow: hidden;
}

.video-card-media {
    width: 100%;
    overflow: hidden;
}

.video-card-media img,
.video-card-media video {
    width: 100%;
    height: auto;
    object-fit: cover;
    display: block;
}

.video-card-caption {
    padding: var(--spacing-md) var(--spacing-lg);
    font-size: var(--font-size-xs);
    color: var(--color-text-muted);
    text-align: center;
}

/* ===== Technical Section ===== */
.technical-section {
    background: var(--color-bg-secondary);
}

.process-steps {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

@media (min-width: 1024px) {
    .process-steps {
        flex-direction: row;
        align-items: flex-start;
        gap: var(--spacing-xl);
    }
}

.step {
    flex: 1;
    display: flex;
    flex-direction: column;
    background: var(--color-bg-card);
    border-radius: var(--border-radius-lg);
    border: 1px solid var(--color-border);
    overflow: hidden;
}

.step-content {
    padding: var(--spacing-lg);
}

.step-content h3 {
    font-size: var(--font-size-base);
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
}

.step-content p {
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
}

/* ===== Dataset / Data Sources Section ===== */
.dataset-section {
    background: var(--color-bg-primary);
}

.data-sources-grid {
    display: grid;
    gap: var(--spacing-lg);
}

@media (min-width: 768px) {
    .data-sources-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (min-width: 1024px) {
    .data-sources-grid {
        grid-template-columns: repeat(4, 1fr);
    }
}

.data-source-card {
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    transition: all var(--transition-fast);
}

.data-source-card:hover {
    border-color: var(--color-accent);
    transform: translateY(-2px);
}

.data-source-card h3 {
    font-size: var(--font-size-base);
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
}

.data-source-card p {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

/* ===== Quick Start Section ===== */
.quickstart-section {
    background: var(--color-bg-secondary);
}

.code-blocks {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xl);
}

.code-block {
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-lg);
    overflow: hidden;
}

.code-block h3 {
    font-size: var(--font-size-base);
    font-weight: 600;
    padding: var(--spacing-md) var(--spacing-lg);
    border-bottom: 1px solid var(--color-border);
    background: var(--color-bg-tertiary);
}

.code-block pre {
    margin: 0;
    padding: var(--spacing-lg);
    overflow-x: auto;
}

.code-block code {
    font-family: 'Menlo', 'Monaco', 'Courier New', monospace;
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    line-height: 1.7;
    white-space: pre;
}

/* ===== Citation Section ===== */
.citation-section {
    background: var(--color-bg-primary);
    border-top: 1px solid var(--color-border);
}

.citation-box {
    position: relative;
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    overflow: hidden;
}

.citation-box pre {
    margin: 0;
    overflow-x: auto;
}

.citation-box code {
    font-family: 'Menlo', 'Monaco', 'Courier New', monospace;
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    line-height: 1.6;
    white-space: pre;
}

.citation-box .copy-btn {
    position: absolute;
    top: var(--spacing-md);
    right: var(--spacing-md);
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--color-accent);
    color: var(--color-text-primary);
    font-size: var(--font-size-sm);
    font-weight: 500;
    border-radius: var(--border-radius-md);
    transition: all var(--transition-fast);
}

.citation-box .copy-btn:hover {
    background: var(--color-accent-hover);
}

/* ===== Resources Section ===== */
.resources-section {
    background: var(--color-bg-secondary);
}

.resources-grid {
    display: grid;
    gap: var(--spacing-xl);
}

@media (min-width: 768px) {
    .resources-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

.resource-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    padding: var(--spacing-2xl);
    background: var(--color-bg-card);
    border-radius: var(--border-radius-lg);
    border: 1px solid var(--color-border);
    transition: all var(--transition-fast);
}

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

.resource-icon {
    width: 64px;
    height: 64px;
    background: var(--color-accent-light);
    border-radius: var(--border-radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-lg);
}

.resource-icon svg {
    width: 32px;
    height: 32px;
    color: var(--color-accent);
}

.resource-card h3 {
    font-size: var(--font-size-xl);
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
}

.resource-card p {
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
}

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

.hero-content,
.hero-banner {
    animation: fadeInUp 0.6s ease-out;
}

.hero-banner {
    animation-delay: 0.2s;
}

/* ===== Scrollbar Styling ===== */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: var(--color-bg-secondary);
}

::-webkit-scrollbar-thumb {
    background: var(--color-bg-tertiary);
    border-radius: var(--border-radius-full);
}

::-webkit-scrollbar-thumb:hover {
    background: var(--color-text-muted);
}

/* ===== Selection Styling ===== */
::selection {
    background: var(--color-accent);
    color: var(--color-text-primary);
}