:root {
    --bg: #0f1419;
    --surface: #1a2332;
    --surface-2: #243044;
    --text: #e8edf4;
    --text-muted: #8b9cb3;
    --accent: #3b82f6;
    --accent-hover: #2563eb;
    --border: #2d3a4f;
    --bar-default: #3b82f6;
    --bar-comparing: #eab308;
    --bar-swapping: #ef4444;
    --bar-sorted: #22c55e;
    --radius: 10px;
    --shadow: 0 4px 24px rgba(0, 0, 0, 0.35);
}

*, *::before, *::after {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    width: min(1200px, 100% - 2rem);
    margin-inline: auto;
}

.header {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header__inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    padding: 0.75rem 0;
    flex-wrap: wrap;
}

.logo {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text);
    text-decoration: none;
    letter-spacing: -0.02em;
}

.logo span {
    color: var(--accent);
}

.nav {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.nav__btn {
    background: transparent;
    border: 1px solid var(--border);
    color: var(--text-muted);
    padding: 0.5rem 1rem;
    border-radius: var(--radius);
    cursor: pointer;
    font-size: 0.9rem;
    transition: all 0.15s ease;
}

.nav__btn:hover {
    color: var(--text);
    border-color: var(--accent);
}

.nav__btn--active {
    background: var(--accent);
    border-color: var(--accent);
    color: #fff;
}

.main {
    flex: 1;
    padding: 2rem 0 3rem;
}

.tab {
    display: none;
}

.tab--active {
    display: block;
}

.page-title {
    margin: 0 0 0.5rem;
    font-size: clamp(1.5rem, 4vw, 2rem);
    font-weight: 700;
}

.page-subtitle {
    margin: 0 0 1.5rem;
    color: var(--text-muted);
}

.patterns-layout {
    display: grid;
    grid-template-columns: 280px 1fr;
    gap: 1.5rem;
    align-items: start;
}

.patterns-list {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    max-height: 70vh;
    overflow-y: auto;
}

.pattern-item {
    display: block;
    width: 100%;
    text-align: left;
    padding: 0.85rem 1rem;
    background: none;
    border: none;
    border-bottom: 1px solid var(--border);
    color: var(--text);
    cursor: pointer;
    transition: background 0.15s;
}

.pattern-item:hover,
.pattern-item--active {
    background: var(--surface-2);
}

.pattern-item__name {
    display: block;
    font-weight: 600;
    font-size: 0.95rem;
}

.pattern-item__cat {
    display: block;
    font-size: 0.75rem;
    color: var(--text-muted);
    text-transform: capitalize;
    margin-top: 0.15rem;
}

.pattern-detail {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.5rem;
    min-height: 400px;
}

.pattern-detail h2 {
    margin: 0 0 0.25rem;
}

.badge {
    display: inline-block;
    font-size: 0.75rem;
    padding: 0.2rem 0.6rem;
    border-radius: 999px;
    background: var(--surface-2);
    color: var(--accent);
    margin-bottom: 1rem;
}

.pattern-section {
    margin-top: 1.5rem;
}

.pattern-section h3 {
    margin: 0 0 0.75rem;
    font-size: 1rem;
    color: var(--text-muted);
}

.mermaid-wrap {
    background: #fff;
    border-radius: var(--radius);
    padding: 1rem;
    overflow-x: auto;
}

.code-block {
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1rem;
    overflow-x: auto;
    font-family: "Cascadia Code", "Fira Code", monospace;
    font-size: 0.85rem;
    white-space: pre-wrap;
}

.pros-cons {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}

.pros-cons ul {
    margin: 0;
    padding-left: 1.25rem;
}

.pros-cons li {
    margin-bottom: 0.35rem;
    font-size: 0.9rem;
}

.algo-controls {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem 1.5rem;
    align-items: flex-end;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.25rem;
    margin-bottom: 1.5rem;
}

.control {
    display: flex;
    flex-direction: column;
    gap: 0.4rem;
    font-size: 0.85rem;
    color: var(--text-muted);
    min-width: 140px;
}

.control select,
.control input[type="range"] {
    accent-color: var(--accent);
}

.control select {
    background: var(--bg);
    border: 1px solid var(--border);
    color: var(--text);
    padding: 0.5rem;
    border-radius: 6px;
}

.control--buttons {
    flex-direction: row;
    align-items: center;
    gap: 0.5rem;
}

.btn {
    background: var(--surface-2);
    border: 1px solid var(--border);
    color: var(--text);
    padding: 0.55rem 1.1rem;
    border-radius: var(--radius);
    cursor: pointer;
    font-size: 0.9rem;
    transition: background 0.15s;
}

.btn:hover {
    background: var(--border);
}

.btn--primary {
    background: var(--accent);
    border-color: var(--accent);
    color: #fff;
}

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

.canvas-wrap {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1rem;
    overflow-x: auto;
}

#sort-canvas {
    display: block;
    width: 100%;
    max-width: 900px;
    height: auto;
    border-radius: 6px;
    background: var(--bg);
}

.legend {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    margin-top: 1rem;
    font-size: 0.85rem;
}

.legend__item {
    display: flex;
    align-items: center;
    gap: 0.4rem;
}

.legend__item::before {
    content: "";
    width: 14px;
    height: 14px;
    border-radius: 3px;
}

.legend__item--default::before { background: var(--bar-default); }
.legend__item--comparing::before { background: var(--bar-comparing); }
.legend__item--swapping::before { background: var(--bar-swapping); }
.legend__item--sorted::before { background: var(--bar-sorted); }

.ws-status {
    margin-top: 0.75rem;
    font-size: 0.8rem;
    color: var(--text-muted);
}

.ws-status--connected {
    color: var(--bar-sorted);
}

.empty-state {
    color: var(--text-muted);
    text-align: center;
    padding: 3rem 1rem;
}

.empty-state--large {
    background: var(--surface);
    border: 1px dashed var(--border);
    border-radius: var(--radius);
    padding: 4rem 2rem;
}

.loading {
    padding: 1.5rem;
    color: var(--text-muted);
    text-align: center;
}

.footer {
    border-top: 1px solid var(--border);
    padding: 1.25rem 0;
    text-align: center;
    font-size: 0.85rem;
    color: var(--text-muted);
}

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

    .patterns-list {
        max-height: 240px;
    }

    .pros-cons {
        grid-template-columns: 1fr;
    }

    .algo-controls {
        flex-direction: column;
        align-items: stretch;
    }

    .control {
        min-width: unset;
    }
}