/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

/* Typography - Distill.pub inspired */
:root {
    --font-serif: 'Georgia', 'Times New Roman', serif;
    --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    --font-mono: 'Menlo', 'Monaco', 'Consolas', monospace;
    
    /* Colors */
    --color-primary: #1a1a1a;
    --color-secondary: #555;
    --color-accent: #0066cc;
    --color-accent-light: #3385d6;
    --color-background: #ffffff;
    --color-background-alt: #f8f9fa;
    --color-border: #e5e7eb;
    --color-code-bg: #f6f8fa;
    
    /* Spacing */
    --spacing-unit: 8px;
    --content-width: 800px;
    
    /* Animation */
    --transition-speed: 0.3s;
}

body {
    font-family: var(--font-serif);
    font-size: 18px;
    line-height: 1.75;
    color: var(--color-primary);
    background-color: var(--color-background);
    overflow-x: hidden;
}

article {
    max-width: var(--content-width);
    margin: 0 auto;
    padding: calc(var(--spacing-unit) * 6) calc(var(--spacing-unit) * 3);
}

/* Headers */
header {
    text-align: center;
    margin-bottom: calc(var(--spacing-unit) * 8);
    padding-bottom: calc(var(--spacing-unit) * 4);
    border-bottom: 1px solid var(--color-border);
}

h1 {
    font-family: var(--font-sans);
    font-size: 56px;
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: calc(var(--spacing-unit) * 2);
    letter-spacing: -0.02em;
}

h2 {
    font-family: var(--font-sans);
    font-size: 32px;
    font-weight: 600;
    margin-top: calc(var(--spacing-unit) * 8);
    margin-bottom: calc(var(--spacing-unit) * 3);
    letter-spacing: -0.01em;
}

h3 {
    font-family: var(--font-sans);
    font-size: 24px;
    font-weight: 600;
    margin-top: calc(var(--spacing-unit) * 4);
    margin-bottom: calc(var(--spacing-unit) * 2);
}

h4 {
    font-family: var(--font-sans);
    font-size: 20px;
    font-weight: 600;
    margin-top: calc(var(--spacing-unit) * 3);
    margin-bottom: calc(var(--spacing-unit) * 2);
}

.subtitle {
    font-family: var(--font-sans);
    font-size: 24px;
    color: var(--color-secondary);
    font-weight: 400;
    margin-bottom: calc(var(--spacing-unit) * 2);
}

.author {
    font-family: var(--font-sans);
    font-size: 16px;
    color: var(--color-secondary);
    font-style: italic;
}

/* Paragraphs and Text */
p {
    margin-bottom: calc(var(--spacing-unit) * 3);
}

em {
    font-style: italic;
}

strong {
    font-weight: 600;
}

ul, ol {
    margin-left: calc(var(--spacing-unit) * 4);
    margin-bottom: calc(var(--spacing-unit) * 3);
}

li {
    margin-bottom: calc(var(--spacing-unit) * 1);
}

/* Sections */
section {
    margin-bottom: calc(var(--spacing-unit) * 10);
}

/* Figures and Captions */
.figure {
    margin: calc(var(--spacing-unit) * 4) 0;
    text-align: center;
}

.caption {
    font-family: var(--font-sans);
    font-size: 14px;
    color: var(--color-secondary);
    margin-top: calc(var(--spacing-unit) * 2);
}

/* Algorithm Box */
.algorithm-box {
    background-color: var(--color-background-alt);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    padding: calc(var(--spacing-unit) * 3);
    margin: calc(var(--spacing-unit) * 4) 0;
}

.algorithm-box h3 {
    margin-top: 0;
}

.algorithm-note {
    margin-top: calc(var(--spacing-unit) * 2);
    padding: calc(var(--spacing-unit) * 2);
    background-color: #f5f5f5;
    border-left: 3px solid var(--color-accent);
    font-style: italic;
    font-size: 16px;
}

/* Code Blocks */
pre {
    background-color: var(--color-code-bg);
    border: 1px solid var(--color-border);
    border-radius: 6px;
    padding: calc(var(--spacing-unit) * 2);
    overflow-x: auto;
    margin-bottom: calc(var(--spacing-unit) * 3);
}

code {
    font-family: var(--font-mono);
    font-size: 14px;
    line-height: 1.5;
}

/* Visualization Guide */
.visualization-guide {
    background-color: #f0f7ff;
    border: 1px solid #d0e5ff;
    border-radius: 8px;
    padding: calc(var(--spacing-unit) * 3);
    margin: calc(var(--spacing-unit) * 3) 0;
}

.visualization-guide h3 {
    font-family: var(--font-sans);
    font-size: 18px;
    margin-bottom: calc(var(--spacing-unit) * 2);
    color: var(--color-accent);
}

.visualization-guide ul {
    margin-left: calc(var(--spacing-unit) * 3);
    margin-bottom: calc(var(--spacing-unit) * 2);
}

.visualization-guide li {
    margin-bottom: calc(var(--spacing-unit) * 1);
    line-height: 1.6;
}

.visualization-guide .tip {
    margin-top: calc(var(--spacing-unit) * 2);
    padding: calc(var(--spacing-unit) * 2);
    background-color: #fffbf0;
    border-left: 3px solid #f0b400;
    font-size: 16px;
    font-style: italic;
}

/* Interactive Elements */
.interactive-container {
    background-color: var(--color-background-alt);
    border-radius: 12px;
    padding: calc(var(--spacing-unit) * 4);
    margin: calc(var(--spacing-unit) * 4) 0;
}

.controls {
    display: flex;
    gap: calc(var(--spacing-unit) * 2);
    align-items: center;
    flex-wrap: wrap;
    margin-bottom: calc(var(--spacing-unit) * 4);
    padding-bottom: calc(var(--spacing-unit) * 3);
    border-bottom: 1px solid var(--color-border);
}

.control-btn {
    font-family: var(--font-sans);
    font-size: 16px;
    padding: calc(var(--spacing-unit) * 1.5) calc(var(--spacing-unit) * 3);
    background-color: var(--color-accent);
    color: white;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    transition: all var(--transition-speed);
}

.control-btn:hover {
    background-color: var(--color-accent-light);
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
}

.control-btn:active {
    transform: translateY(0);
}

.speed-control {
    display: flex;
    align-items: center;
    gap: calc(var(--spacing-unit) * 2);
    margin-left: auto;
}

.speed-control label {
    font-family: var(--font-sans);
    font-size: 14px;
    color: var(--color-secondary);
}

.speed-control input[type="range"] {
    width: 150px;
}

/* Visualization Area */
.visualization-area {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: calc(var(--spacing-unit) * 4);
    margin-bottom: calc(var(--spacing-unit) * 4);
}

.current-permutation {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: calc(var(--spacing-unit) * 2);
    font-size: 48px;
    font-family: var(--font-sans);
    font-weight: 600;
    min-height: 120px;
}

.perm-element {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 80px;
    height: 80px;
    background-color: white;
    border: 3px solid var(--color-border);
    border-radius: 12px;
    transition: all var(--transition-speed);
}

.perm-element.swapping {
    background-color: var(--color-accent);
    color: white;
    transform: scale(1.1);
    border-color: var(--color-accent);
}

.swap-indicator {
    font-family: var(--font-sans);
    font-size: 16px;
    color: var(--color-secondary);
    text-align: center;
    min-height: 30px;
}

/* Algorithm State */
.algorithm-state {
    background-color: white;
    border: 1px solid var(--color-border);
    border-radius: 8px;
    padding: calc(var(--spacing-unit) * 3);
}

.algorithm-state h4 {
    margin-top: 0;
}

#state-display {
    display: flex;
    flex-direction: column;
    gap: calc(var(--spacing-unit) * 1.5);
}

.state-item {
    display: flex;
    justify-content: space-between;
    font-family: var(--font-sans);
    font-size: 14px;
}

.state-label {
    color: var(--color-secondary);
}

/* Permutation History */
.permutation-history {
    margin-top: calc(var(--spacing-unit) * 4);
}

.history-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
    gap: calc(var(--spacing-unit) * 2);
    max-height: 300px;
    overflow-y: auto;
    padding: calc(var(--spacing-unit) * 2);
    background-color: white;
    border: 1px solid var(--color-border);
    border-radius: 8px;
}

.history-item {
    font-family: var(--font-mono);
    font-size: 14px;
    padding: calc(var(--spacing-unit) * 1);
    background-color: var(--color-background-alt);
    border-radius: 4px;
    text-align: center;
    transition: all var(--transition-speed);
}

.history-item.new {
    background-color: var(--color-accent);
    color: white;
}

/* Tree Visualization */
.tree-visualization {
    margin: calc(var(--spacing-unit) * 4) 0;
    overflow-x: auto;
}

.tree-visualization svg {
    display: block;
    margin: 0 auto;
}

/* Implementation Tabs */
.implementation-tabs {
    margin: calc(var(--spacing-unit) * 4) 0;
}

.tab-buttons {
    display: flex;
    gap: calc(var(--spacing-unit) * 1);
    border-bottom: 2px solid var(--color-border);
}

.tab-btn {
    font-family: var(--font-sans);
    font-size: 16px;
    padding: calc(var(--spacing-unit) * 2) calc(var(--spacing-unit) * 3);
    background: none;
    border: none;
    cursor: pointer;
    color: var(--color-secondary);
    transition: all var(--transition-speed);
    border-bottom: 3px solid transparent;
    margin-bottom: -2px;
}

.tab-btn:hover {
    color: var(--color-primary);
}

.tab-btn.active {
    color: var(--color-accent);
    border-bottom-color: var(--color-accent);
}

.tab-content {
    display: none;
    margin-top: calc(var(--spacing-unit) * 3);
}

.tab-content.active {
    display: block;
}

/* Performance Chart */
.performance-comparison {
    margin: calc(var(--spacing-unit) * 4) 0;
    text-align: center;
}

#performance-chart {
    max-width: 100%;
    height: auto;
}

/* Algorithm Explanation */
.algorithm-explanation {
    background-color: var(--color-background-alt);
    border-radius: 12px;
    padding: calc(var(--spacing-unit) * 4);
    margin: calc(var(--spacing-unit) * 4) 0;
}

.algorithm-explanation h3 {
    margin-top: 0;
    color: var(--color-accent);
}

.key-points {
    background-color: white;
    border: 1px solid var(--color-border);
    border-radius: 8px;
    padding: calc(var(--spacing-unit) * 3);
    margin: calc(var(--spacing-unit) * 3) 0;
}

.key-points h4 {
    margin-top: 0;
    margin-bottom: calc(var(--spacing-unit) * 2);
}

.key-points ul {
    margin-bottom: 0;
}

.key-points li {
    margin-bottom: calc(var(--spacing-unit) * 1.5);
}

.key-points li:last-child {
    margin-bottom: 0;
}

.counter-example {
    background-color: var(--color-code-bg);
    border: 1px solid var(--color-border);
    border-radius: 6px;
    padding: calc(var(--spacing-unit) * 2);
    margin: calc(var(--spacing-unit) * 2) 0;
    font-family: var(--font-mono);
    font-size: 14px;
    line-height: 1.8;
}

.chart-note {
    font-style: italic;
    color: var(--color-secondary);
    text-align: center;
    margin-top: calc(var(--spacing-unit) * 2);
    margin-bottom: calc(var(--spacing-unit) * 3);
}

/* Complexity Table */
.complexity-table {
    overflow-x: auto;
    margin: calc(var(--spacing-unit) * 4) 0;
}

table {
    width: 100%;
    border-collapse: collapse;
    font-family: var(--font-sans);
    font-size: 16px;
}

th, td {
    padding: calc(var(--spacing-unit) * 2);
    text-align: left;
    border-bottom: 1px solid var(--color-border);
}

th {
    background-color: var(--color-background-alt);
    font-weight: 600;
}

tbody tr:hover {
    background-color: var(--color-background-alt);
}

/* Applications Grid */
.applications-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: calc(var(--spacing-unit) * 3);
    margin: calc(var(--spacing-unit) * 4) 0;
}

.application-card {
    background-color: var(--color-background-alt);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    padding: calc(var(--spacing-unit) * 3);
    transition: all var(--transition-speed);
}

.application-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.application-card h3 {
    margin-top: 0;
    margin-bottom: calc(var(--spacing-unit) * 2);
    color: var(--color-accent);
}

.application-card p {
    font-size: 16px;
    margin-bottom: 0;
}

/* Permutation List */
.permutation-list {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: calc(var(--spacing-unit) * 2);
    max-width: 400px;
    margin: 0 auto;
}

.perm-item {
    font-family: var(--font-mono);
    font-size: 18px;
    padding: calc(var(--spacing-unit) * 2);
    background-color: var(--color-background-alt);
    border: 1px solid var(--color-border);
    border-radius: 6px;
    text-align: center;
    transition: all var(--transition-speed);
}

.perm-item.highlight {
    background-color: var(--color-accent);
    color: white;
    transform: scale(1.05);
}

/* Footer */
footer {
    text-align: center;
    padding: calc(var(--spacing-unit) * 8) calc(var(--spacing-unit) * 3);
    border-top: 1px solid var(--color-border);
    margin-top: calc(var(--spacing-unit) * 10);
}

footer p {
    font-family: var(--font-sans);
    font-size: 14px;
    color: var(--color-secondary);
    margin-bottom: 0;
}

/* Responsive Design */
@media (max-width: 768px) {
    body {
        font-size: 16px;
    }
    
    h1 {
        font-size: 40px;
    }
    
    h2 {
        font-size: 28px;
    }
    
    h3 {
        font-size: 20px;
    }
    
    .subtitle {
        font-size: 20px;
    }
    
    article {
        padding: calc(var(--spacing-unit) * 4) calc(var(--spacing-unit) * 2);
    }
    
    .visualization-area {
        grid-template-columns: 1fr;
    }
    
    .current-permutation {
        font-size: 36px;
    }
    
    .perm-element {
        width: 60px;
        height: 60px;
    }
    
    .controls {
        justify-content: center;
    }
    
    .speed-control {
        margin-left: 0;
        width: 100%;
    }
    
    .applications-grid {
        grid-template-columns: 1fr;
    }
}

/* Scrollbar styling */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

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

::-webkit-scrollbar-thumb {
    background: var(--color-border);
    border-radius: 4px;
}

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