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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.6;
    color: #f0f0f0;
    background-color: #050505;
}

header {
    background: linear-gradient(135deg, #101010 0%, #232323 100%);
    color: white;
    padding: 3rem 2rem;
    text-align: center;
    border-bottom: 1px solid #222;
    opacity: 0;
    transform: translateY(-30px);
    transition: opacity 1s cubic-bezier(0.4, 0, 0.2, 1), transform 1s cubic-bezier(0.4, 0, 0.2, 1);
}

header.visible {
    opacity: 1;
    transform: translateY(0);
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
    font-weight: 300;
    letter-spacing: -0.5px;
}

header p {
    opacity: 0.6;
    font-weight: 300;
}

/* Demo sections - Two column layout */
.demo-section {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    max-width: 1400px;
    margin: 0 auto;
    padding: 8rem 4rem;
    min-height: 100vh;
    align-items: center;
    opacity: 0;
    transition: opacity 1.2s ease-out;
}

.demo-section.visible {
    opacity: 1;
}

/* Text column */
.demo-text {
    opacity: 0;
    transform: translateX(-50px);
    transition: opacity 0.8s ease-out 0.2s, transform 0.8s ease-out 0.2s;
}

.demo-section.visible .demo-text {
    opacity: 1;
    transform: translateX(0);
}

.demo-text h2 {
    font-size: 2.5rem;
    font-weight: 300;
    margin-bottom: 1.5rem;
    color: #ffffff;
    letter-spacing: -1px;
}

.demo-text p {
    font-size: 1.1rem;
    line-height: 1.8;
    color: #b0b0b0;
    margin-bottom: 2rem;
    font-weight: 300;
}

/* Visualization column */
.demo-viz {
    opacity: 0;
    transform: translateX(50px);
    transition: opacity 0.8s ease-out 0.4s, transform 0.8s ease-out 0.4s;
}

.demo-section.visible .demo-viz {
    opacity: 1;
    transform: translateX(0);
}

/* Expandable Detailed Explanation */
.expand-btn {
    margin-top: 1.5rem;
    margin-bottom: 0.5rem;
    background: transparent;
    border: 1px solid #333;
    color: #999;
    padding: 0.7rem 1.2rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.7rem;
    font-size: 0.9rem;
    font-weight: 300;
    border-radius: 3px;
    width: fit-content;
    opacity: 0;
    transform: translateY(10px);
    transition: opacity 0.7s cubic-bezier(0.4, 0, 0.2, 1) 0.8s, transform 0.7s cubic-bezier(0.4, 0, 0.2, 1) 0.8s, border-color 0.2s, color 0.2s;
}

.expand-btn.visible {
    opacity: 1;
    transform: translateY(0);
}

.expand-btn:hover {
    border-color: #555;
    color: #fff;
}

.expand-btn .icon {
    transition: transform 0.3s ease;
    font-size: 0.8rem;
}

.expand-btn.expanded .icon {
    transform: rotate(180deg);
}

.detailed-content {
    max-height: 0;
    overflow: hidden;
    border-left: 2px solid #222;
    padding-left: 1.5rem;
    margin-top: 1rem;
    opacity: 0;
    transform: translateY(-8px);
    transition: max-height 0.7s cubic-bezier(0.4, 0, 0.2, 1), opacity 0.7s cubic-bezier(0.4, 0, 0.2, 1), transform 0.7s cubic-bezier(0.4, 0, 0.2, 1), padding-top 0.7s cubic-bezier(0.4, 0, 0.2, 1);
}

.detailed-content.visible {
    max-height: 500px;
    padding-top: 0.5rem;
    opacity: 1;
    transform: translateY(0);
}

.detailed-content p {
    font-size: 0.95rem;
    line-height: 1.7;
    color: #aaa;
    margin-bottom: 1rem;
}

.detailed-content strong {
    color: #fff;
    font-weight: 400;
}

/* Controls */
.controls {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    margin-top: 2rem;
    padding: 1.5rem;
    background: #121212;
    border: 1px solid #2a2a2a;
    border-radius: 4px;
    opacity: 0;
    transform: translateY(15px);
    visibility: hidden;
    transition: opacity 0.8s cubic-bezier(0.4, 0, 0.2, 1), transform 0.8s cubic-bezier(0.4, 0, 0.2, 1), visibility 0s 0.8s;
}

.controls.delayed-hidden {
    display: none;
}

.controls.delayed-shown {
    display: flex;
    visibility: visible;
    opacity: 1;
    transform: translateY(0);
    transition: opacity 0.8s cubic-bezier(0.4, 0, 0.2, 1), transform 0.8s cubic-bezier(0.4, 0, 0.2, 1), visibility 0s;
}

.controls label {
    font-weight: 300;
    color: #999;
    font-size: 0.9rem;
}

#lr-value, #epoch-slider-value {
    color: #fff;
    font-weight: 500;
}

input[type="range"] {
    width: 100%;
    cursor: pointer;
    accent-color: #666;
    height: 2px;
}

.controls > div:first-child {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.controls > div:last-child {
    display: flex;
    gap: 0.5rem;
}

button {
    background: #232323;
    color: #f2f2f2;
    border: 1px solid #3a3a3a;
    padding: 0.6rem 1.2rem;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.85rem;
    transition: all 0.2s;
    font-weight: 300;
}

button:hover {
    background: #333333;
    border-color: #666666;
}

button:active {
    transform: scale(0.98);
}

/* Visualizations */
#gradient-viz, #boundary-viz, #optimizer-viz, #loss-viz {
    margin: 0 auto;
}

#bias-variance-viz {
    margin: 0 auto;
}

/* Bias-Variance section special layout */
.bias-variance-section {
    min-height: auto;
    padding: 6rem 4rem;
}

/* Scroll section - sticky layout */
.scroll-section {
    grid-template-columns: 1fr 1fr;
    min-height: 200vh;
    align-items: flex-start;
    padding-top: 10vh;
}

.sticky-text {
    position: sticky;
    top: 10vh;
    height: fit-content;
}

.sticky-viz {
    position: sticky;
    top: 10vh;
    height: fit-content;
}

.scroll-progress {
    margin-top: 2rem;
    font-size: 0.9rem;
    color: #666;
    font-weight: 300;
}

.scroll-spacer {
    grid-column: 1 / -1;
    height: 100vh;
}

/* References Section */
.references-section {
    background: #101010;
    border-top: 1px solid #2a2a2a;
    padding: 6rem 4rem;
}

.references-container {
    max-width: 1400px;
    margin: 0 auto;
}

.references-container h2 {
    font-size: 2rem;
    font-weight: 300;
    margin-bottom: 2rem;
    color: #ffffff;
    text-align: center;
    letter-spacing: -0.5px;
}

.about-text {
    max-width: 900px;
    margin: 0 auto 3rem;
    text-align: left;
}

.about-text p {
    font-size: 1.05rem;
    line-height: 1.8;
    color: #b0b0b0;
    margin-bottom: 1.5rem;
    font-weight: 300;
}

.references-container a {
    text-decoration: none;
    transition: color 0.2s;
}

.references-container a:hover {
    color: #fff;
}

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

.reference-item h3 {
    font-size: 1.1rem;
    font-weight: 400;
    color: #fff;
    margin-bottom: 1rem;
    letter-spacing: -0.3px;
}

.reference-item ul {
    list-style: none;
    padding: 0;
}

.reference-item li {
    color: #999;
    font-size: 0.95rem;
    line-height: 1.8;
    padding-left: 1rem;
    position: relative;
    font-weight: 300;
}

.reference-item li:before {
    content: "→";
    position: absolute;
    left: 0;
    color: #666;
}

.references-citation {
    border-top: 1px solid #1a1a1a;
    padding-top: 2rem;
    margin-top: 2rem;
}

.references-citation strong {
    color: #fff;
    font-weight: 400;
}

.citation {
    color: #777;
    font-size: 0.9rem;
    line-height: 1.6;
    margin: 0.5rem 0;
    font-weight: 300;
}

.citation em {
    font-style: italic;
    color: #888;
}

/* Footer */
footer {
    background: #000;
    color: #666;
    text-align: center;
    padding: 2rem;
    border-top: 1px solid #222;
    font-weight: 300;
    font-size: 0.9rem;
}

/* SVG axis styling for minimal look */
.axis path,
.axis line {
    stroke: #555;
    stroke-width: 1;
}

.axis text {
    fill: #999;
    font-size: 11px;
    font-weight: 300;
}

.grid line {
    stroke: #2a2a2a;
    stroke-opacity: 0.8;
}

.grid path {
    stroke-width: 0;
}

text {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

.legend {
    font-size: 11px;
    fill: #b0b0b0;
}

/* Responsive */
@media (max-width: 1024px) {
    .demo-section {
        grid-template-columns: 1fr;
        gap: 3rem;
        padding: 4rem 2rem;
    }
    
    .demo-text {
        transform: translateY(-30px);
    }
    
    .demo-viz {
        transform: translateY(30px);
    }
    
    .demo-section.visible .demo-text,
    .demo-section.visible .demo-viz {
        transform: translateY(0);
    }
    
    .scroll-section {
        grid-template-columns: 1fr;
    }
    
    .references-grid {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
    
    .references-section {
        padding: 4rem 2rem;
    }
}