/* Root variables for theming */
:root {
    /* Light theme (default) */
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-card: #ffffff;
    --text-primary: #212529;
    --text-secondary: #6c757d;
    --text-muted: #adb5bd;
    --border-color: #dee2e6;
    --link-color: #0066cc;
    --link-hover: #0052a3;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
    --tooltip-bg: #ffffff;
    --tooltip-border: #dee2e6;
    --canvas-border: #dee2e6;
    --button-bg: #f8f9fa;
    --button-hover: #e9ecef;
    --button-active: #dee2e6;
}

[data-theme="dark"] {
    /* Dark theme */
    --bg-primary: #1a1a1a;
    --bg-secondary: #2d2d2d;
    --bg-card: #242424;
    --text-primary: #e9ecef;
    --text-secondary: #adb5bd;
    --text-muted: #6c757d;
    --border-color: #495057;
    --link-color: #66b3ff;
    --link-hover: #4da3ff;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.3);
    --tooltip-bg: #2d2d2d;
    --tooltip-border: #495057;
    --canvas-border: #495057;
    --button-bg: #2d2d2d;
    --button-hover: #3a3a3a;
    --button-active: #495057;
}

/* Reset and base styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background: var(--bg-primary);
    transition: background-color 0.3s ease, color 0.3s ease;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    width: 100%;
}

/* Header */
header {
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 0;
    margin-bottom: 2rem;
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.header-nav {
    display: flex;
    align-items: center;
    gap: 2rem;
}

/* Theme toggle button */
.theme-toggle {
    background: var(--button-bg);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    padding: 0.5rem 0.75rem;
    cursor: pointer;
    font-size: 1.2rem;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 44px;
}

.theme-toggle:hover {
    background: var(--button-hover);
    transform: scale(1.05);
}

.theme-toggle:active {
    background: var(--button-active);
    transform: scale(0.95);
}

/* Main content */
main {
    flex: 1;
    padding-bottom: 4rem;
}

/* Typography */
h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    letter-spacing: -0.02em;
    background: linear-gradient(135deg, var(--text-primary) 0%, var(--text-secondary) 100%);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

h2 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-secondary);
}

.subtitle {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: 3rem;
}

/* Navigation links */
.nav-link {
    color: var(--text-primary);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
}

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

/* Dataset cards */
.dataset-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
    margin-top: 2rem;
}

.dataset-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 1.5rem;
    transition: all 0.3s ease;
    text-decoration: none;
    display: block;
    box-shadow: var(--shadow-sm);
}

.dataset-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--link-color);
}

.dataset-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.dataset-card p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.5;
}

/* Heatmap page */
.controls {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 1.5rem;
    margin-bottom: 2rem;
    box-shadow: var(--shadow-sm);
}

.controls-row {
    display: flex;
    flex-wrap: wrap;
    gap: 1.5rem;
    align-items: center;
}

.control-group {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

/* Checkboxes */
.checkbox-wrapper {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.checkbox-wrapper input[type="checkbox"] {
    width: 20px;
    height: 20px;
    cursor: pointer;
    accent-color: var(--link-color);
}

.checkbox-wrapper label {
    cursor: pointer;
    font-weight: 500;
    color: var(--text-primary);
    user-select: none;
}

/* Canvas */
.heatmap-container {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 1.5rem;
    box-shadow: var(--shadow-md);
    overflow-x: auto;
}

canvas {
    border: 2px solid var(--canvas-border);
    border-radius: 4px;
    max-width: 100%;
    height: auto;
    display: block;
    margin: 0 auto;
    /* Avoid browser blurring */
    image-rendering: optimizeSpeed;
    image-rendering: -moz-crisp-edges;
    image-rendering: -o-crisp-edges;
    image-rendering: -webkit-optimize-contrast;
    image-rendering: pixelated;
    image-rendering: optimize-contrast;
    -ms-interpolation-mode: nearest-neighbor;
}

/* Tooltip */
.tooltip {
    position: absolute;
    background: var(--tooltip-bg);
    border: 1px solid var(--tooltip-border);
    border-radius: 4px;
    padding: 12px;
    display: none;
    width: 220px;
    box-shadow: var(--shadow-lg);
    pointer-events: none;
    z-index: 1000;
    transition: opacity 0.3s ease;
}

.tooltip img {
    max-width: 100%;
    border-radius: 4px;
    margin-top: 8px;
}

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

.tooltip em {
    color: var(--text-muted);
}

/* Video section */
.video-section {
    margin-top: 4rem;
    text-align: center;
}

.video-section h3 {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 2rem;
}

.video-container {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 100%;
}

.youtube-player {
    max-width: 100%;
    height: auto;
    aspect-ratio: 16 / 10;
    box-shadow: var(--shadow-lg);
    border-radius: 6px;
}

/* Footer */
footer {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-color);
    padding: 2rem 0;
    margin-top: auto;
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}

footer p {
    color: var(--text-secondary);
    margin: 0;
    font-size: 0.95rem;
}

footer a {
    color: var(--link-color);
    text-decoration: none;
    transition: color 0.3s ease;
}

footer a:hover {
    color: var(--link-hover);
    text-decoration: underline;
}

/* Responsive design */
@media (max-width: 768px) {
    h1 {
        font-size: 2rem;
    }
    
    .dataset-grid {
        grid-template-columns: 1fr;
    }
    
    .header-content {
        flex-direction: column;
        gap: 1rem;
    }
    
    .controls-row {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .footer-content {
        flex-direction: column;
        text-align: center;
    }
}

@media (max-width: 480px) {
    h1 {
        font-size: 1.75rem;
    }
    
    .container {
        padding: 0 15px;
    }
    
    .tooltip {
        width: 180px;
    }
}

/* Loading animation */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid var(--border-color);
    border-radius: 50%;
    border-top-color: var(--link-color);
    animation: spin 1s ease-in-out infinite;
}

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

/* Smooth transitions */
* {
    transition: background-color 0.3s ease, border-color 0.3s ease, color 0.3s ease;
}