/* ── reset & base ── */
*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --sidebar-width: 260px;
    --sidebar-bg: #0e1a2b;
    --sidebar-text: #c8d6e5;
    --sidebar-active: #3b82f6;
    --sidebar-hover: #1e2a3a;
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --bg: #f1f5f9;
    --surface: #ffffff;
    --text: #0f172a;
    --text-secondary: #334155;
    --border: #e2e8f0;
    --code-bg: #f1f5f9;
    --code-border: #e2e8f0;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.06);
    --radius: 8px;
    --transition: 0.2s ease;
    --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    --font-mono: 'JetBrains Mono', 'Cascadia Code', 'Fira Code', 'Consolas', monospace;
}

html {
    font-size: 16px;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: var(--font);
    background: var(--bg);
    color: var(--text);
    display: flex;
    min-height: 100vh;
    line-height: 1.6;
    overflow-x: hidden;
}

a {
    color: var(--primary);
    text-decoration: none;
    transition: color var(--transition);
}
a:hover {
    color: var(--primary-dark);
    text-decoration: underline;
}

/* ── scrollbar ── */
::-webkit-scrollbar {
    width: 6px;
    height: 6px;
}
::-webkit-scrollbar-track {
    background: transparent;
}
::-webkit-scrollbar-thumb {
    background: #94a3b8;
    border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
    background: #64748b;
}

/* ── skip link ── */
.skip-link {
    position: absolute;
    left: 12px;
    top: -60px;
    background: var(--primary);
    color: #fff;
    padding: 10px 18px;
    border-radius: var(--radius);
    z-index: 300;
    font-weight: 600;
    font-size: 0.9rem;
    transition: top var(--transition);
}
.skip-link:focus {
    top: 12px;
}

/* ── sidebar ── */
.sidebar {
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    width: var(--sidebar-width);
    background: var(--sidebar-bg);
    color: var(--sidebar-text);
    display: flex;
    flex-direction: column;
    overflow-y: auto;
    overflow-x: hidden;
    z-index: 100;
    transition: transform var(--transition);
    will-change: transform;
    border-right: 1px solid rgba(255, 255, 255, 0.05);
}

.sidebar-brand {
    padding: 20px 20px 14px 20px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.06);
    flex-shrink: 0;
}

.sidebar-brand a {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.15rem;
    font-weight: 600;
    color: #fff;
    text-decoration: none;
    letter-spacing: -0.01em;
}
.sidebar-brand a:hover {
    text-decoration: none;
    color: #fff;
}
.sidebar-brand .brand-icon {
    font-size: 1.4rem;
    line-height: 1;
}
.sidebar-brand .brand-sub {
    font-size: 0.7rem;
    font-weight: 400;
    opacity: 0.5;
    display: block;
    margin-top: 1px;
    letter-spacing: 0.02em;
}

.sidebar-nav {
    padding: 12px 0 20px 0;
    flex: 1;
}

.sidebar-section {
    margin-bottom: 4px;
}

.sidebar-section-title {
    padding: 6px 20px 4px 20px;
    font-size: 0.65rem;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    font-weight: 600;
    color: rgba(255, 255, 255, 0.25);
    cursor: default;
    user-select: none;
}

.sidebar-item {
    display: block;
    padding: 6px 20px 6px 20px;
    color: var(--sidebar-text);
    text-decoration: none;
    font-size: 0.9rem;
    border-left: 3px solid transparent;
    transition: background var(--transition), border-color var(--transition), color var(--transition);
    cursor: pointer;
    position: relative;
}
.sidebar-item:hover {
    background: var(--sidebar-hover);
    color: #fff;
    text-decoration: none;
}
.sidebar-item.active {
    background: rgba(59, 130, 246, 0.15);
    border-left-color: var(--sidebar-active);
    color: #fff;
    font-weight: 500;
}
.sidebar-item .item-label {
    display: inline-block;
}
.sidebar-item .item-tag {
    font-size: 0.6rem;
    background: rgba(255, 255, 255, 0.06);
    padding: 1px 8px;
    border-radius: 12px;
    margin-left: 8px;
    color: rgba(255, 255, 255, 0.3);
    font-weight: 400;
    letter-spacing: 0.01em;
}

/* ── sidebar toggle (mobile) ── */
.sidebar-toggle {
    display: none;
    position: fixed;
    top: 12px;
    left: 12px;
    z-index: 200;
    background: var(--sidebar-bg);
    color: #fff;
    border: none;
    border-radius: var(--radius);
    padding: 8px 12px;
    font-size: 1.3rem;
    cursor: pointer;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
    transition: background var(--transition);
    line-height: 1;
}
.sidebar-toggle:hover {
    background: #1a2a3e;
}
.sidebar-toggle .close-icon {
    display: none;
}
.sidebar-open .sidebar-toggle .menu-icon {
    display: none;
}
.sidebar-open .sidebar-toggle .close-icon {
    display: inline;
}

.sidebar-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.3);
    z-index: 90;
    opacity: 0;
    transition: opacity 0.25s ease;
}
.sidebar-open .sidebar-overlay {
    display: block;
    opacity: 1;
}

/* ── main content ── */
.main {
    margin-left: var(--sidebar-width);
    flex: 1;
    min-height: 100vh;
    padding: 40px 48px 60px 48px;
    max-width: 1000px;
    transition: margin var(--transition);
}

.page {
    display: none;
    animation: fadeIn 0.25s ease;
}
.page.active {
    display: block;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(6px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.page-header {
    margin-bottom: 28px;
    padding-bottom: 16px;
    border-bottom: 2px solid var(--border);
}
.page-header h1 {
    font-size: 2rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    line-height: 1.2;
    color: var(--text);
}
.page-header .page-sub {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-top: 4px;
}

.page-content {
    font-size: 0.95rem;
    color: var(--text-secondary);
    line-height: 1.7;
}
.page-content h2 {
    font-size: 1.5rem;
    font-weight: 600;
    margin: 1.8em 0 0.5em 0;
    color: var(--text);
    letter-spacing: -0.01em;
}
.page-content h3 {
    font-size: 1.2rem;
    font-weight: 600;
    margin: 1.6em 0 0.4em 0;
    color: var(--text);
}
.page-content h4 {
    font-size: 1.05rem;
    font-weight: 600;
    margin: 1.4em 0 0.3em 0;
    color: var(--text);
}
.page-content p {
    margin: 0 0 1em 0;
}
.page-content ul,
.page-content ol {
    margin: 0 0 1em 1.8em;
}
.page-content li {
    margin-bottom: 0.3em;
}
.page-content blockquote {
    border-left: 4px solid var(--primary);
    padding: 0.6em 1.2em;
    margin: 1em 0;
    background: var(--bg);
    border-radius: 0 var(--radius) var(--radius) 0;
    color: var(--text-secondary);
}
.page-content blockquote p:last-child {
    margin-bottom: 0;
}

.page-content code {
    font-family: var(--font-mono);
    font-size: 0.85em;
    background: var(--code-bg);
    padding: 0.15em 0.5em;
    border-radius: 4px;
    border: 1px solid var(--code-border);
    color: #1e293b;
}
.page-content pre {
    font-family: var(--font-mono);
    font-size: 0.82rem;
    background: #0f172a;
    color: #e2e8f0;
    padding: 1.2em 1.4em;
    border-radius: var(--radius);
    overflow-x: auto;
    margin: 1em 0;
    line-height: 1.5;
    border: 1px solid #1e293b;
}
.page-content pre code {
    background: transparent;
    padding: 0;
    border: none;
    color: inherit;
    font-size: inherit;
}

.page-content table {
    width: 100%;
    border-collapse: collapse;
    margin: 1.2em 0;
    font-size: 0.9rem;
}
.page-content table th,
.page-content table td {
    padding: 0.6em 1em;
    border: 1px solid var(--border);
    text-align: left;
}
.page-content table th {
    background: var(--bg);
    font-weight: 600;
    color: var(--text);
}
.page-content table tr:nth-child(even) {
    background: rgba(241, 245, 249, 0.4);
}

.page-content hr {
    border: none;
    border-top: 2px solid var(--border);
    margin: 2em 0;
}

.page-content .file-tree {
    font-family: var(--font-mono);
    font-size: 0.82rem;
    background: var(--bg);
    padding: 1.2em 1.6em;
    border-radius: var(--radius);
    border: 1px solid var(--border);
    overflow-x: auto;
    white-space: pre;
    line-height: 1.6;
    color: var(--text-secondary);
}

.page-content .note {
    background: #fefce8;
    border: 1px solid #fde68a;
    border-radius: var(--radius);
    padding: 0.8em 1.2em;
    margin: 1em 0;
    color: #78350f;
}
.page-content .note strong {
    color: #92400e;
}

.page-content .badge {
    display: inline-block;
    background: var(--primary);
    color: #fff;
    font-size: 0.7rem;
    font-weight: 600;
    padding: 0.1em 0.7em;
    border-radius: 12px;
    letter-spacing: 0.02em;
}

.page-content .spec-grid {
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 0.4em 1.2em;
    background: var(--bg);
    padding: 0.8em 1.2em;
    border-radius: var(--radius);
    border: 1px solid var(--border);
    margin: 0.8em 0;
    font-size: 0.9rem;
}
.page-content .spec-grid .label {
    font-weight: 600;
    color: var(--text);
}

/* ── responsive ── */
@media (max-width: 820px) {
    .sidebar {
        transform: translateX(-100%);
        width: 280px;
    }
    .sidebar-open .sidebar {
        transform: translateX(0);
    }
    .sidebar-toggle {
        display: block;
    }
    .main {
        margin-left: 0;
        padding: 24px 20px 40px 20px;
    }
    .page-header h1 {
        font-size: 1.6rem;
    }
    .page-content {
        font-size: 0.92rem;
    }
    .page-content .file-tree {
        font-size: 0.7rem;
        padding: 0.8em 1em;
    }
    .sidebar-open .main {
        filter: blur(2px);
        pointer-events: none;
        user-select: none;
    }
}

@media (max-width: 480px) {
    .main {
        padding: 16px 14px 32px 14px;
    }
    .page-header h1 {
        font-size: 1.3rem;
    }
    .page-content table {
        font-size: 0.78rem;
    }
    .page-content table th,
    .page-content table td {
        padding: 0.4em 0.6em;
    }
    .page-content pre {
        font-size: 0.7rem;
        padding: 0.8em 1em;
    }
    .page-content .file-tree {
        font-size: 0.65rem;
        padding: 0.6em 0.8em;
    }
    .sidebar {
        width: 260px;
    }
    .sidebar-brand a {
        font-size: 1rem;
    }
    .sidebar-item {
        font-size: 0.85rem;
        padding: 5px 16px 5px 16px;
    }
}

@media (min-width: 1400px) {
    .main {
        padding: 48px 56px 80px 56px;
        max-width: 1100px;
    }
    .page-content {
        font-size: 1rem;
    }
}

/* ── print ── */
@media print {
    .sidebar,
    .sidebar-toggle,
    .sidebar-overlay {
        display: none !important;
    }
    .main {
        margin-left: 0 !important;
        padding: 20px !important;
        max-width: 100% !important;
    }
    .page {
        display: block !important;
    }
    .page:not(.active) {
        display: none !important;
    }
    .page-content pre {
        background: #f1f5f9 !important;
        color: #0f172a !important;
        border: 1px solid #e2e8f0 !important;
    }
    .page-content .file-tree {
        background: #f1f5f9 !important;
        border: 1px solid #e2e8f0 !important;
    }
}

/* ── motion & focus ── */
.page-header h1:focus-visible {
    outline: 2px solid var(--primary);
    outline-offset: 4px;
    border-radius: 2px;
}

@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.001ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.001ms !important;
        scroll-behavior: auto !important;
    }
}