:root {
    --bg-primary: #0a0e14;
    --bg-secondary: #131820;
    --bg-tertiary: #1a2130;
    --accent-blue: #39bae6;
    --accent-green: #7fd962;
    --accent-orange: #ff9940;
    --accent-red: #f26d6d;
    --accent-purple: #c792ea;
    --accent-pink: #f07178;
    --accent-yellow: #ffe585;
    --text-primary: #e6e6e6;
    --text-secondary: #707a8c;
    --border-color: #2a3444;
    --connect4-blue: #0066cc;
    --connect4-red: #e63946;
    --connect4-yellow: #ffd60a;
}

/* Light theme */
[data-theme="light"] {
    --bg-primary: #f5f5f5;
    --bg-secondary: #ffffff;
    --bg-tertiary: #e8e8e8;
    --text-primary: #1a1a1a;
    --text-secondary: #666666;
    --border-color: #d0d0d0;
}

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

body {
    font-family: 'Nunito', sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.8;
}

/* Theme Toggle */
.theme-toggle {
    position: fixed;
    top: 1rem;
    right: 1rem;
    z-index: 1000;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    cursor: pointer;
    font-size: 1.2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s;
}

.theme-toggle:hover {
    background: var(--accent-blue);
    transform: scale(1.1);
}

/* Hero */
.hero {
    min-height: 45vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: 3rem 2rem;
    background: linear-gradient(180deg, #131820 0%, #0a0e14 100%);
    border-bottom: 1px solid var(--border-color);
}

.hero h1 {
    font-size: 3rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
    background: linear-gradient(135deg, var(--connect4-red), var(--connect4-yellow));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero p {
    font-size: 1.2rem;
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

.story-intro {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
    justify-content: center;
}

.chapter-badge {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    padding: 0.4rem 1rem;
    border-radius: 20px;
    font-size: 0.85rem;
    color: var(--accent-yellow);
}

/* Container & Sections */
.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

.story-section {
    padding: 4rem 0;
    border-bottom: 1px solid var(--border-color);
}

/* Chapter Headers */
.chapter-header {
    margin-bottom: 2rem;
}

.chapter-number {
    display: inline-block;
    background: var(--accent-purple);
    color: var(--bg-primary);
    padding: 0.3rem 1rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 700;
    text-transform: uppercase;
    margin-bottom: 0.5rem;
}

.chapter-header h2 {
    font-size: 2rem;
    color: var(--text-primary);
}

/* Story Text */
.story-text {
    margin-bottom: 1.5rem;
}

.story-text p {
    margin-bottom: 1rem;
}

.story-text h3 {
    font-size: 1.3rem;
    color: var(--accent-green);
    margin: 2rem 0 1rem;
}

.story-text ol,
.story-text ul {
    margin-left: 1.5rem;
    margin-bottom: 1rem;
}

.story-text li {
    margin-bottom: 0.5rem;
}

.highlight {
    color: var(--accent-orange);
    font-weight: 600;
}

/* Roadmap */
.roadmap {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    flex-wrap: wrap;
    margin: 2rem 0;
    padding: 1.5rem;
    background: var(--bg-secondary);
    border-radius: 12px;
    border: 1px solid var(--border-color);
}

.roadmap-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    background: var(--bg-tertiary);
    border-radius: 8px;
    font-size: 0.9rem;
}

.roadmap-item.final-item {
    background: rgba(127, 217, 98, 0.15);
    border: 1px solid var(--accent-green);
}

.roadmap-icon {
    font-size: 1.2rem;
}

.roadmap-arrow {
    color: var(--text-secondary);
}

/* Final Goal / Preview */
.final-goal {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 2rem;
    text-align: center;
    margin: 2rem 0;
}

.final-goal h3 {
    color: var(--accent-yellow);
    margin-bottom: 1.5rem;
}

/* Connect4 Preview Grid */
.connect4-preview {
    display: grid;
    grid-template-columns: repeat(7, 50px);
    grid-template-rows: repeat(6, 50px);
    gap: 4px;
    margin: 0 auto 1.5rem;
    width: fit-content;
    background: var(--connect4-blue);
    padding: 8px;
    border-radius: 8px;
}

.preview-cell {
    width: 50px;
    height: 50px;
    background: var(--bg-primary);
    border-radius: 50%;
    cursor: pointer;
    transition: all 0.2s;
}

.preview-cell:hover {
    background: rgba(255, 255, 255, 0.2);
}

.preview-cell.player1 {
    background: var(--connect4-red);
    box-shadow: inset 0 -3px 6px rgba(0, 0, 0, 0.3);
}

.preview-cell.player2 {
    background: var(--connect4-yellow);
    box-shadow: inset 0 -3px 6px rgba(0, 0, 0, 0.2);
}

/* Legend */
.legend {
    display: flex;
    gap: 2rem;
    justify-content: center;
    flex-wrap: wrap;
    margin: 1rem 0;
}

.legend-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.9rem;
}

.legend-box {
    width: 24px;
    height: 24px;
    border-radius: 50%;
}

.player1-box {
    background: var(--connect4-red);
}

.player2-box {
    background: var(--connect4-yellow);
}

/* Concept Box */
.concept-box {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 2rem;
    margin: 1.5rem 0;
}

.flow-diagram {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
}

.flow-box {
    background: var(--bg-tertiary);
    border: 2px solid var(--border-color);
    padding: 1rem 2rem;
    border-radius: 8px;
    text-align: center;
    min-width: 180px;
}

.flow-box.setup-box {
    border-color: var(--accent-blue);
}

.flow-box.draw-box {
    border-color: var(--accent-green);
}

.flow-label {
    font-family: 'JetBrains Mono', monospace;
    font-weight: 600;
    font-size: 1.1rem;
    display: block;
}

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

.flow-arrow-down {
    font-size: 1.5rem;
    color: var(--text-secondary);
}

/* Code Block */
.code-block {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    margin: 1.5rem 0;
    overflow: hidden;
}

.code-header {
    background: var(--bg-tertiary);
    padding: 0.75rem 1rem;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
    color: var(--text-secondary);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

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

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

.code-dots .red {
    background: var(--accent-red);
}

.code-dots .yellow {
    background: var(--accent-orange);
}

.code-dots .green {
    background: var(--accent-green);
}

.version-badge {
    background: var(--accent-purple);
    color: white;
    padding: 0.2rem 0.6rem;
    border-radius: 4px;
    font-size: 0.7rem;
    font-weight: 700;
}

pre {
    padding: 1.25rem;
    overflow-x: auto;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
    line-height: 1.6;
}

/* Syntax */
.keyword {
    color: var(--accent-purple);
}

.string {
    color: var(--accent-green);
}

.number {
    color: var(--accent-orange);
}

.function {
    color: var(--accent-blue);
}

.comment {
    color: var(--text-secondary);
    font-style: italic;
}

.variable {
    color: var(--accent-pink);
}

.new-code {
    background: rgba(127, 217, 98, 0.1);
    display: inline;
}

.new-line {
    background: rgba(127, 217, 98, 0.15);
    display: block;
    padding: 0 0.5rem;
    margin: 0 -0.5rem;
    border-left: 3px solid var(--accent-green);
}

code {
    font-family: 'JetBrains Mono', monospace;
    background: var(--bg-tertiary);
    padding: 0.15rem 0.4rem;
    border-radius: 4px;
    font-size: 0.85rem;
}

/* Interactive Demo */
.interactive-demo {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    overflow: hidden;
    margin: 1.5rem 0;
}

.demo-header {
    background: var(--bg-tertiary);
    padding: 0.75rem 1rem;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.demo-title {
    font-weight: 600;
    color: var(--accent-yellow);
}

.demo-btn {
    background: var(--accent-blue);
    color: var(--bg-primary);
    border: none;
    padding: 0.5rem 1.25rem;
    border-radius: 6px;
    cursor: pointer;
    font-family: 'Nunito', sans-serif;
    font-weight: 600;
    font-size: 0.9rem;
    transition: all 0.2s;
}

.demo-btn:hover {
    background: var(--accent-purple);
    transform: translateY(-2px);
}

.demo-content {
    padding: 1.5rem;
}

.demo-explanation {
    margin-bottom: 1rem;
    font-size: 0.95rem;
}

/* Calculator */
.calculator-v4 {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.calc-slider {
    display: flex;
    align-items: center;
    gap: 1rem;
    flex-wrap: wrap;
}

.calc-slider input[type="range"] {
    flex: 1;
    min-width: 150px;
}

.calc-i-value {
    font-family: 'JetBrains Mono', monospace;
    font-size: 2rem;
    font-weight: 700;
    color: var(--accent-orange);
    min-width: 50px;
    text-align: center;
}

.calc-formulas {
    display: flex;
    gap: 2rem;
    flex-wrap: wrap;
    justify-content: center;
}

.calc-formula-box {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.9rem;
}

.calc-formula-label {
    color: var(--text-secondary);
}

.calc-formula-result {
    font-size: 1.1rem;
}

.calc-formula-result strong {
    color: var(--accent-green);
}

/* Click Demo Grid */
.click-demo-grid {
    display: grid;
    grid-template-columns: repeat(7, 50px);
    grid-template-rows: repeat(6, 50px);
    gap: 4px;
    margin: 0 auto;
    width: fit-content;
    background: var(--connect4-blue);
    padding: 8px;
    border-radius: 8px;
}

.click-demo-cell {
    width: 50px;
    height: 50px;
    background: var(--bg-primary);
    border-radius: 50%;
    cursor: pointer;
    transition: all 0.2s;
}

.click-demo-cell:hover {
    background: rgba(255, 255, 255, 0.3);
}

.click-info {
    text-align: center;
    margin-top: 1rem;
    font-family: 'JetBrains Mono', monospace;
    color: var(--accent-yellow);
}

/* Console Output */
.console-output {
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1rem;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.8rem;
    max-height: 180px;
    overflow-y: auto;
}

.console-line {
    margin: 0.2rem 0;
    white-space: pre-wrap;
    word-break: break-word;
}

.console-line.dim {
    color: var(--text-secondary);
}

.console-line.output {
    color: var(--accent-green);
}

.console-line.error {
    color: var(--accent-red);
}

/* Info Box */
.info-box {
    background: rgba(57, 186, 230, 0.1);
    border-left: 4px solid var(--accent-blue);
    padding: 1.25rem;
    border-radius: 0 8px 8px 0;
    margin: 1.5rem 0;
}

.info-box ul {
    margin: 0.75rem 0 0 1.5rem;
}

.info-box li {
    margin-bottom: 0.4rem;
}

/* Array Explanation */
.array-explanation {
    margin: 1.5rem 0;
}

.array-box {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1rem;
}

.array-box h4 {
    font-size: 0.9rem;
    margin-bottom: 0.75rem;
    color: var(--accent-blue);
}

/* Four Directions */
.four-directions {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1rem;
    margin: 1.5rem 0;
}

.direction-card {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 1.5rem;
    text-align: center;
    transition: all 0.3s;
}

.direction-card:hover {
    border-color: var(--accent-blue);
    transform: translateY(-3px);
}

.direction-icon {
    font-size: 2rem;
    margin-bottom: 0.5rem;
}

.direction-name {
    font-weight: 600;
    color: var(--accent-yellow);
    margin-bottom: 0.5rem;
}

.direction-visual {
    font-size: 1rem;
    line-height: 1.2;
}

.direction-visual.diagonal {
    text-align: left;
    display: inline-block;
}

.direction-visual.diagonal-reverse {
    text-align: right;
    display: inline-block;
}

/* Win Check Demo */
.win-check-demo {
    display: grid;
    grid-template-columns: repeat(7, 40px);
    grid-template-rows: repeat(6, 40px);
    gap: 3px;
    margin: 0 auto 1rem;
    width: fit-content;
    background: var(--connect4-blue);
    padding: 6px;
    border-radius: 6px;
}

.win-check-cell {
    width: 40px;
    height: 40px;
    background: var(--bg-primary);
    border-radius: 50%;
    transition: all 0.3s;
}

.win-check-cell.player1 {
    background: var(--connect4-red);
}

.win-check-cell.player2 {
    background: var(--connect4-yellow);
}

.win-check-cell.checking {
    box-shadow: 0 0 10px var(--accent-yellow);
}

.win-check-cell.winning {
    box-shadow: 0 0 15px var(--accent-green);
    animation: pulse 0.5s infinite alternate;
}

@keyframes pulse {
    from {
        transform: scale(1);
    }

    to {
        transform: scale(1.1);
    }
}

/* Success Box */
.success-box {
    background: rgba(127, 217, 98, 0.1);
    border: 2px solid var(--accent-green);
    border-radius: 12px;
    overflow: hidden;
    margin: 1.5rem 0;
}

.success-header {
    background: var(--accent-green);
    color: var(--bg-primary);
    padding: 0.75rem 1rem;
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.success-header h3 {
    font-size: 1rem;
}

.success-content {
    padding: 1.25rem;
}

.success-content ul {
    margin: 0.75rem 0 0 1.5rem;
}

/* Final Game Grid */
.connect4-grid {
    display: grid;
    grid-template-columns: repeat(7, 55px);
    grid-template-rows: repeat(6, 55px);
    gap: 4px;
    margin: 0 auto 1rem;
    width: fit-content;
    background: var(--connect4-blue);
    padding: 10px;
    border-radius: 10px;
    box-shadow: 0 4px 20px rgba(0, 102, 204, 0.3);
}

.game-cell {
    width: 55px;
    height: 55px;
    background: var(--bg-primary);
    border-radius: 50%;
    cursor: pointer;
    transition: all 0.2s;
    position: relative;
}

.game-cell:hover {
    background: rgba(255, 255, 255, 0.2);
}

.game-cell.player1 {
    background: var(--connect4-red);
    box-shadow: inset 0 -4px 8px rgba(0, 0, 0, 0.3), 0 2px 4px rgba(0, 0, 0, 0.2);
    cursor: default;
}

.game-cell.player2 {
    background: var(--connect4-yellow);
    box-shadow: inset 0 -4px 8px rgba(0, 0, 0, 0.2), 0 2px 4px rgba(0, 0, 0, 0.2);
    cursor: default;
}

.game-cell.winning {
    animation: winPulse 0.6s infinite alternate;
}

@keyframes winPulse {
    from {
        transform: scale(1);
        box-shadow: inset 0 -4px 8px rgba(0, 0, 0, 0.3), 0 0 0 rgba(255, 255, 255, 0);
    }

    to {
        transform: scale(1.05);
        box-shadow: inset 0 -4px 8px rgba(0, 0, 0, 0.3), 0 0 15px rgba(255, 255, 255, 0.5);
    }
}

/* Score Display */
.score-display {
    display: flex;
    justify-content: center;
    gap: 3rem;
    margin-bottom: 1rem;
    font-size: 1.1rem;
    font-weight: 600;
}

.player1-score {
    color: var(--connect4-red);
}

.player2-score {
    color: var(--connect4-yellow);
}

/* Game Status */
.game-status {
    text-align: center;
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-top: 1rem;
}

.game-message {
    text-align: center;
    font-size: 1.3rem;
    font-weight: 700;
    margin-top: 0.5rem;
    min-height: 2rem;
}

.game-message.win-red {
    color: var(--connect4-red);
}

.game-message.win-yellow {
    color: var(--connect4-yellow);
}

.game-message.draw {
    color: var(--accent-purple);
}

/* Summary Table */
.lessons-learned {
    margin: 2rem 0;
}

.lessons-learned h3 {
    color: var(--accent-purple);
    margin-bottom: 1rem;
}

.summary-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.9rem;
}

.summary-table th,
.summary-table td {
    padding: 0.75rem;
    text-align: left;
    border: 1px solid var(--border-color);
}

.summary-table th {
    background: var(--bg-tertiary);
    color: var(--accent-blue);
}

.summary-table td {
    background: var(--bg-secondary);
}

.summary-table td:last-child {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.8rem;
    color: var(--text-secondary);
}

/* Evolution Timeline */
.evolution-timeline {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    flex-wrap: wrap;
    margin: 2rem 0;
    padding: 1.5rem;
    background: var(--bg-secondary);
    border-radius: 12px;
}

.timeline-item {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1rem;
    text-align: center;
    min-width: 120px;
}

.timeline-item.final {
    border-color: var(--accent-green);
}

.timeline-version {
    font-family: 'JetBrains Mono', monospace;
    font-weight: 700;
    font-size: 1.1rem;
    color: var(--accent-purple);
    margin-bottom: 0.5rem;
}

.timeline-content h4 {
    font-size: 0.85rem;
    margin-bottom: 0.25rem;
}

.timeline-content p {
    font-size: 0.7rem;
    color: var(--text-secondary);
}

.timeline-arrow {
    color: var(--text-secondary);
    font-size: 1.2rem;
}

/* What's Next */
.whats-next {
    background: var(--bg-secondary);
    border: 1px solid var(--accent-yellow);
    border-radius: 12px;
    padding: 1.5rem;
    margin-top: 2rem;
}

.whats-next h3 {
    color: var(--accent-yellow);
    margin-bottom: 1rem;
}

.whats-next ul {
    margin-left: 1.5rem;
}

.whats-next li {
    margin-bottom: 0.5rem;
}

/* Navigation Dots */
.nav-dots {
    position: fixed;
    right: 1.5rem;
    top: 50%;
    transform: translateY(-50%);
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    z-index: 100;
}

.nav-dot {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: var(--border-color);
    cursor: pointer;
    transition: all 0.2s;
}

.nav-dot:hover,
.nav-dot.active {
    background: var(--accent-blue);
    transform: scale(1.4);
}

/* Diagonal Grid Visualization - Proper 45° diagonals */
.diagonal-grid {
    display: grid;
    grid-template-columns: repeat(4, 28px);
    grid-template-rows: repeat(4, 28px);
    gap: 3px;
    margin: 0 auto;
}

.diagonal-cell {
    width: 28px;
    height: 28px;
    background: var(--bg-tertiary);
    border-radius: 50%;
    transition: all 0.3s;
}

.diagonal-cell.active {
    background: var(--connect4-red);
    box-shadow: 0 0 8px var(--connect4-red);
}

/* Direction Cards - Improved Layout */
.direction-card-improved {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 1.25rem;
    text-align: center;
    transition: all 0.3s;
}

.direction-card-improved:hover {
    border-color: var(--accent-blue);
    transform: translateY(-3px);
}

/* Concept Explanation Boxes */
.concept-explain-box {
    background: linear-gradient(135deg, rgba(199, 146, 234, 0.1), rgba(57, 186, 230, 0.1));
    border: 1px solid var(--accent-purple);
    border-radius: 12px;
    padding: 1.5rem;
    margin: 1.5rem 0;
}

.concept-explain-box h4 {
    color: var(--accent-purple);
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.concept-explain-box .visual-example {
    background: var(--bg-primary);
    border-radius: 8px;
    padding: 1rem;
    margin: 1rem 0;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
}

/* Comparison Grid for const vs let */
.comparison-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
}

@media (max-width: 768px) {
    .comparison-grid {
        grid-template-columns: 1fr;
    }
}

.comparison-item {
    background: var(--bg-tertiary);
    padding: 1rem;
    border-radius: 8px;
}

.comparison-item h5 {
    color: var(--accent-blue);
    margin-bottom: 0.75rem;
}

.comparison-item ul {
    margin: 0.5rem 0;
    padding-left: 1.2rem;
    font-size: 0.9rem;
}

.comparison-item li {
    margin: 0.3rem 0;
}

.code-mini {
    background: var(--bg-primary);
    border-radius: 6px;
    padding: 0.75rem;
    margin-top: 0.75rem;
    overflow-x: auto;
}

.code-mini pre {
    margin: 0;
    font-size: 0.8rem;
    color: var(--text-primary);
}

/* Smart Algorithm Comparison */
.algorithm-comparison {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
    margin: 1.5rem 0;
}

@media (max-width: 768px) {
    .algorithm-comparison {
        grid-template-columns: 1fr;
    }
}

.algo-box {
    background: var(--bg-secondary);
    border: 2px solid var(--border-color);
    border-radius: 12px;
    padding: 1.5rem;
}

.algo-box.naive {
    border-color: var(--accent-orange);
}

.algo-box.smart {
    border-color: var(--accent-green);
}

.algo-box h4 {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.algo-box.naive h4 {
    color: var(--accent-orange);
}

.algo-box.smart h4 {
    color: var(--accent-green);
}

.algo-complexity {
    font-family: 'JetBrains Mono', monospace;
    background: var(--bg-tertiary);
    padding: 0.5rem 1rem;
    border-radius: 6px;
    display: inline-block;
    margin-top: 0.5rem;
}

/* Direction Vectors Visualization */
.direction-vectors {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    justify-content: center;
    margin: 1.5rem 0;
}

.vector-card {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 1rem 1.5rem;
    text-align: center;
    min-width: 140px;
}

.vector-arrows {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
}

.vector-code {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.8rem;
    color: var(--accent-blue);
}

/* Smart Algorithm Demo */
.smart-algo-demo {
    display: grid;
    grid-template-columns: repeat(7, 45px);
    grid-template-rows: repeat(6, 45px);
    gap: 3px;
    margin: 0 auto 1rem;
    width: fit-content;
    background: var(--connect4-blue);
    padding: 8px;
    border-radius: 8px;
}

.smart-algo-cell {
    width: 45px;
    height: 45px;
    background: var(--bg-primary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.7rem;
    font-family: 'JetBrains Mono', monospace;
    transition: all 0.3s;
}

.smart-algo-cell.player1 {
    background: var(--connect4-red);
}

.smart-algo-cell.player2 {
    background: var(--connect4-yellow);
}

.smart-algo-cell.current {
    box-shadow: 0 0 15px var(--accent-green);
    animation: pulse 0.5s infinite alternate;
}

.smart-algo-cell.checking {
    box-shadow: 0 0 10px var(--accent-blue);
}

.smart-algo-cell.counted {
    box-shadow: 0 0 10px var(--accent-purple);
}

/* Direction Arrow Lines */
.direction-line {
    position: absolute;
    height: 3px;
    background: var(--accent-green);
    transform-origin: left center;
}

/* Full Code Block - with comments */
.full-code-block pre {
    max-height: 600px;
    overflow-y: auto;
}

/* Expandable Full Code Section */
.full-code-expandable {
    margin-top: 1rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background: var(--bg-secondary);
}

.full-code-expandable summary {
    padding: 0.75rem 1rem;
    cursor: pointer;
    font-weight: 600;
    color: var(--accent-blue);
    display: flex;
    align-items: center;
    gap: 0.5rem;
    user-select: none;
}

.full-code-expandable summary:hover {
    background: var(--bg-tertiary);
}

.full-code-expandable summary::marker {
    display: none;
}

.full-code-expandable summary::before {
    content: "▶";
    font-size: 0.7rem;
    transition: transform 0.2s;
}

.full-code-expandable[open] summary::before {
    transform: rotate(90deg);
}

.full-code-expandable .code-block {
    margin: 0;
    border-radius: 0 0 8px 8px;
    border-top: 1px solid var(--border-color);
}

.full-code-expandable .code-block pre {
    max-height: 500px;
    overflow-y: auto;
}

/* Code Comment Highlight */
.code-comment-important {
    background: rgba(255, 153, 64, 0.15);
    padding: 0.1rem 0.3rem;
    border-radius: 3px;
}

/* Step Counter Animation */
.step-counter {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin: 1rem 0;
    padding: 1rem;
    background: var(--bg-tertiary);
    border-radius: 8px;
}

.step-counter .count-display {
    font-family: 'JetBrains Mono', monospace;
    font-size: 2rem;
    font-weight: 700;
    color: var(--accent-green);
    min-width: 60px;
    text-align: center;
}

/* Responsive */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 2rem;
    }

    .roadmap {
        flex-direction: column;
        align-items: flex-start;
    }

    .roadmap-arrow {
        transform: rotate(90deg);
        align-self: center;
    }

    .four-directions {
        grid-template-columns: repeat(2, 1fr);
    }

    .evolution-timeline {
        flex-direction: column;
    }

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

    .nav-dots {
        display: none;
    }

    .connect4-preview,
    .click-demo-grid,
    .connect4-grid {
        transform: scale(0.85);
        transform-origin: center;
    }

    .score-display {
        gap: 1.5rem;
        font-size: 1rem;
    }
}

@media (max-width: 480px) {

    .connect4-preview,
    .click-demo-grid,
    .connect4-grid {
        transform: scale(0.7);
    }
}