:root {
    --bg: #ffffff;
    --bg-elevated: #f6f8fa;
    --bg-code: #f4f4f6;
    --fg: #1f2328;
    --fg-muted: #59636e;
    --border: #d1d9e0;
    --accent: #0969da;
    --accent-bg: #ddf4ff;

    --syntax-comment:  #6a737d;
    --syntax-punct:    #24292e;
    --syntax-number:   #005cc5;
    --syntax-string:   #032f62;
    --syntax-keyword:  #d73a49;
    --syntax-function: #6f42c1;
    --syntax-variable: #e36209;

    --sidebar-width: 240px;
    --toc-width: 200px;
    --content-max: 760px;
    --header-height: 56px;

    --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
    --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
}

[data-theme="dark"] {
    --bg: #1c2028;
    --bg-elevated: #242933;
    --bg-code: #1f242c;
    --fg: #e6edf3;
    --fg-muted: #9da6b3;
    --border: #353b46;
    --accent: #66b1ff;
    --accent-bg: #1f6feb33;

    --syntax-comment:  #8b949e;
    --syntax-punct:    #c9d1d9;
    --syntax-number:   #79c0ff;
    --syntax-string:   #a5d6ff;
    --syntax-keyword:  #ff7b72;
    --syntax-function: #d2a8ff;
    --syntax-variable: #ffa657;
}

* { box-sizing: border-box; }

html, body {
    margin: 0;
    padding: 0;
    font-family: var(--font-sans);
    color: var(--fg);
    background: var(--bg);
    font-size: 16px;
    line-height: 1.6;
}

.sidebar {
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    width: var(--sidebar-width);
    background: var(--bg-elevated);
    border-right: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    z-index: 5;
}

.sidebar-brand {
    display: block;
    font-weight: 600;
    color: var(--fg);
    text-decoration: none;
    font-family: var(--font-mono);
    font-size: 0.95rem;
    padding: 1.25rem 1.25rem 1rem;
    flex: 0 0 auto;
    border-bottom: 1px solid var(--border);
}
.sidebar-brand:hover { color: var(--accent); }

.sidebar-nav {
    flex: 1 1 auto;
    min-height: 0;
    overflow-y: auto;
    padding: 1rem;
    scrollbar-width: thin;
    scrollbar-color: var(--border) transparent;
}
.sidebar-nav::-webkit-scrollbar { width: 10px; }
.sidebar-nav::-webkit-scrollbar-track { background: transparent; }
.sidebar-nav::-webkit-scrollbar-thumb {
    background: var(--border);
    border-radius: 5px;
    border: 3px solid var(--bg-elevated);
    background-clip: padding-box;
}
.sidebar-nav::-webkit-scrollbar-thumb:hover {
    background: var(--fg-muted);
    background-clip: padding-box;
    border: 3px solid var(--bg-elevated);
}

.theme-toggle {
    position: fixed;
    top: 1rem;
    right: 1rem;
    z-index: 6;
    background: var(--bg);
    border: 1px solid var(--border);
    color: var(--fg);
    border-radius: 6px;
    padding: 0.3rem 0.65rem;
    cursor: pointer;
    font-size: 0.9rem;
    line-height: 1;
}
.theme-toggle:hover { border-color: var(--accent); color: var(--accent); }

.layout {
    margin-left: var(--sidebar-width);
    display: grid;
    grid-template-columns: minmax(0, 1fr) var(--toc-width);
    gap: 2.5rem;
    max-width: calc(1100px + var(--toc-width));
    padding: 2.5rem 2rem 2.5rem 3.25rem;
    align-items: start;
}

.nav-section { margin-bottom: 1.25rem; }
.nav-section:last-child { margin-bottom: 0; }
.nav-section h4 {
    margin: 0 0 0.4rem;
    padding: 0 0.6rem;
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--fg-muted);
}
.nav-section ul {
    list-style: none;
    margin: 0;
    padding: 0;
}
.nav-section li { margin: 0; }
.nav-section a {
    display: block;
    padding: 0.3rem 0.6rem;
    border-radius: 6px;
    color: var(--fg);
    text-decoration: none;
    font-size: 0.9rem;
}
.nav-section a:hover { background: var(--bg); }
.nav-section a.active {
    background: var(--accent-bg);
    color: var(--accent);
    font-weight: 500;
}

.content { min-width: 0; }

.prose {
    max-width: var(--content-max);
}

.prose h1, .prose h2, .prose h3, .prose h4 {
    position: relative;
    margin-top: 2rem;
    margin-bottom: 0.75rem;
    line-height: 1.25;
    font-weight: 600;
}
.prose h1 { font-size: 2rem; margin-top: 0; border-bottom: 1px solid var(--border); padding-bottom: 0.5rem; }
.prose h2 { font-size: 1.4rem; border-bottom: 1px solid var(--border); padding-bottom: 0.3rem; }
.prose h3 { font-size: 1.15rem; }
.prose h4 { font-size: 1rem; }

.prose p, .prose ul, .prose ol { margin: 0.75rem 0; }
.prose a { color: var(--accent); text-decoration: none; }
.prose a:hover { text-decoration: underline; }

.prose code {
    font-family: var(--font-mono);
    background: var(--bg-code);
    padding: 0.15em 0.35em;
    border-radius: 4px;
    font-size: 0.875em;
}

.prose pre {
    background: var(--bg-code);
    padding: 1rem;
    border-radius: 8px;
    overflow-x: auto;
    border: 1px solid var(--border);
    position: relative;
    color: var(--syntax-punct);
}
.prose pre code {
    background: none;
    padding: 0;
    font-size: 0.875em;
    line-height: 1.5;
    color: inherit;
}

/* Prism token colours, themed via CSS variables. */
.token.comment, .token.prolog, .token.doctype, .token.cdata { color: var(--syntax-comment); font-style: italic; }
.token.punctuation { color: var(--syntax-punct); }
.token.namespace { opacity: 0.7; }
.token.boolean, .token.number, .token.constant, .token.symbol, .token.property,
.token.tag, .token.deleted { color: var(--syntax-number); }
.token.string, .token.char, .token.attr-value, .token.inserted,
.token.selector, .token.builtin { color: var(--syntax-string); }
.token.operator, .token.entity, .token.url { color: var(--syntax-keyword); }
.token.atrule, .token.keyword, .token.important { color: var(--syntax-keyword); font-weight: 500; }
.token.function, .token.class-name { color: var(--syntax-function); }
.token.regex, .token.variable, .token.attr-name { color: var(--syntax-variable); }

.prose blockquote {
    margin: 1rem 0;
    padding: 0.5rem 1rem;
    border-left: 4px solid var(--accent);
    background: var(--bg-elevated);
    color: var(--fg-muted);
}

.prose table {
    border-collapse: collapse;
    margin: 1rem 0;
    width: 100%;
}
.prose th, .prose td {
    border: 1px solid var(--border);
    padding: 0.4rem 0.6rem;
    text-align: left;
}
.prose th { background: var(--bg-elevated); }

.prose .heading-anchor {
    position: absolute;
    right: 100%;
    top: 0;
    padding-right: 0.4em;
    color: var(--fg-muted);
    text-decoration: none;
    font-weight: 400;
    opacity: 0;
    transition: opacity 0.15s;
}
.prose h1:hover .heading-anchor,
.prose h2:hover .heading-anchor,
.prose h3:hover .heading-anchor,
.prose h4:hover .heading-anchor,
.prose .heading-anchor:focus { opacity: 1; }

.toc-sidebar {
    position: sticky;
    top: 2.5rem;
    max-height: calc(100vh - 5rem);
    overflow-y: auto;
    font-size: 0.875rem;
    scrollbar-width: thin;
    scrollbar-color: var(--border) transparent;
}
.toc-sidebar h4 {
    margin: 0 0 0.4rem;
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--fg-muted);
}
.toc-sidebar ul {
    list-style: none;
    padding: 0;
    margin: 0;
}
.toc-sidebar li { margin: 0.25rem 0; }
.toc-sidebar a {
    color: var(--fg-muted);
    text-decoration: none;
    display: block;
    padding: 0.1rem 0;
    border-left: 2px solid transparent;
    padding-left: 0.6rem;
    margin-left: -0.6rem;
}
.toc-sidebar a:hover { color: var(--accent); }

.page-nav {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin-top: 3rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--border);
}
.page-nav a {
    display: block;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border);
    border-radius: 8px;
    text-decoration: none;
    color: var(--fg);
}
.page-nav a:hover { border-color: var(--accent); }
.page-nav-next { text-align: right; }
.page-nav-label {
    display: block;
    font-size: 0.75rem;
    color: var(--fg-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}
.page-nav-title { font-weight: 500; }

@media (max-width: 1100px) {
    .layout {
        grid-template-columns: 1fr;
    }
    .toc-sidebar { display: none; }
}

@media (max-width: 800px) {
    .sidebar {
        position: static;
        width: auto;
        height: auto;
        display: block;
        border-right: none;
        border-bottom: 1px solid var(--border);
    }
    .sidebar-nav { overflow: visible; padding: 0.5rem 1rem 1rem; }
    .layout {
        margin-left: 0;
        padding: 1.5rem 1rem;
    }
    .theme-toggle { top: 0.6rem; right: 0.6rem; }
}