:root {
    --bg: #fafafa;
    --fg: #222;
    --muted: #666;
    --accent: #0a6ed1;
    --border: #e5e5e5;
    --code-bg: #f4f4f4;
    --callout-bg: #fff8e1;
    --callout-border: #e6c200;
}

* { box-sizing: border-box; }

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background: var(--bg);
    color: var(--fg);
    line-height: 1.65;
    max-width: 760px;
    margin: 0 auto;
    padding: 2rem 1.25rem 4rem;
    font-size: 17px;
}

header.site {
    border-bottom: 1px solid var(--border);
    padding-bottom: 1rem;
    margin-bottom: 2rem;
    font-size: 0.9rem;
    color: var(--muted);
}

header.site a {
    color: var(--muted);
    text-decoration: none;
}

header.site a:hover { color: var(--accent); }

h1 { font-size: 2rem; line-height: 1.25; margin-top: 0.5rem; }
h2 { font-size: 1.35rem; margin-top: 2.2rem; border-bottom: 1px solid var(--border); padding-bottom: 0.3rem; }
h3 { font-size: 1.1rem; margin-top: 1.8rem; }

p, li { font-size: 1rem; }

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

code {
    background: var(--code-bg);
    padding: 0.1rem 0.35rem;
    border-radius: 3px;
    font-size: 0.9em;
    font-family: "SF Mono", Menlo, Consolas, monospace;
}

pre {
    background: var(--code-bg);
    padding: 0.9rem 1rem;
    border-radius: 4px;
    overflow-x: auto;
    font-size: 0.88rem;
    line-height: 1.5;
}

pre code {
    background: transparent;
    padding: 0;
}

blockquote {
    border-left: 3px solid var(--accent);
    margin: 1.2rem 0;
    padding: 0.2rem 1rem;
    color: var(--muted);
    background: #fff;
}

.callout {
    background: var(--callout-bg);
    border-left: 4px solid var(--callout-border);
    padding: 0.8rem 1rem;
    border-radius: 3px;
    margin: 1.2rem 0;
    font-size: 0.95rem;
}

.callout strong { color: #7a5d00; }

.callout.tech {
    background: #eef5fc;
    border-left-color: var(--accent);
}
.callout.tech strong { color: #084e93; }

table {
    border-collapse: collapse;
    width: 100%;
    margin: 1.2rem 0;
    font-size: 0.93rem;
}

th, td {
    border: 1px solid var(--border);
    padding: 0.5rem 0.75rem;
    text-align: left;
    vertical-align: top;
}

th { background: #f0f0f0; }

nav.series {
    margin-top: 3rem;
    padding-top: 1.2rem;
    border-top: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
    font-size: 0.95rem;
}

nav.series a.spacer { visibility: hidden; }

ol.toc { padding-left: 1.2rem; }
ol.toc li { margin: 0.5rem 0; }

.subtitle {
    color: var(--muted);
    font-size: 1.05rem;
    margin-top: -0.5rem;
    margin-bottom: 1.5rem;
}

.tag {
    display: inline-block;
    font-size: 0.7rem;
    font-weight: 600;
    letter-spacing: 0.03em;
    text-transform: uppercase;
    padding: 0.1rem 0.45rem;
    border-radius: 3px;
    vertical-align: middle;
    margin-left: 0.4rem;
}
.tag.concept { background: #e7f1ff; color: #084e93; }
.tag.build { background: #eafaef; color: #1a7f37; }

.mermaid {
    background: #fff;
    border: 1px solid var(--border);
    border-radius: 4px;
    padding: 1rem;
    margin: 1.5rem 0;
    text-align: center;
    overflow-x: auto;
}

.diagram-caption {
    text-align: center;
    color: var(--muted);
    font-size: 0.85rem;
    margin-top: -1rem;
    margin-bottom: 1.5rem;
}

footer.site {
    margin-top: 4rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border);
    font-size: 0.85rem;
    color: var(--muted);
}