/* TrueBooks Support — static, self-contained, no external dependencies. */

:root {
  --bg:           #ffffff;
  --bg-soft:      #f7f8fb;
  --bg-muted:     #eef0f5;
  --border:       #e3e6ee;
  --border-soft:  #eef0f5;
  --fg:           #14181f;
  --fg-soft:      #4a5160;
  --fg-muted:     #6b7384;
  --primary:      hsl(226, 81%, 34%);
  --primary-soft: hsl(226, 81%, 95%);
  --primary-fg:   #ffffff;
  --link:         hsl(226, 81%, 38%);
  --code-bg:      #f1f2f6;
  --shadow-sm:    0 1px 2px rgba(20, 24, 31, 0.04);
  --radius:       8px;
  --radius-sm:    6px;
  --max-content:  760px;
  --max-page:     1180px;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  color: var(--fg);
  background: var(--bg);
  font: 16px/1.6 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a { color: var(--link); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 3px; }

code, pre {
  font-family: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
  font-size: 0.92em;
}
code {
  background: var(--code-bg);
  padding: 0.1em 0.4em;
  border-radius: 4px;
}
pre {
  background: var(--code-bg);
  padding: 14px 16px;
  border-radius: var(--radius-sm);
  overflow-x: auto;
  border: 1px solid var(--border);
}
pre code { background: transparent; padding: 0; }

/* ── Header ────────────────────────────────────────────────────────────── */

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(255,255,255,0.85);
  backdrop-filter: saturate(140%) blur(8px);
  -webkit-backdrop-filter: saturate(140%) blur(8px);
  border-bottom: 1px solid var(--border);
}
.site-header-inner {
  max-width: var(--max-page);
  margin: 0 auto;
  padding: 12px 24px;
  display: flex;
  align-items: center;
  gap: 24px;
}
.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 600;
  color: var(--fg);
}
.brand:hover { text-decoration: none; }
.brand img { height: 28px; width: auto; display: block; }
.brand .pipe {
  color: var(--fg-muted);
  font-weight: 300;
}
.brand .label {
  color: var(--fg-soft);
  font-weight: 500;
  font-size: 0.95em;
}
.spacer { flex: 1; }
.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 14px;
  border-radius: var(--radius-sm);
  font-weight: 500;
  font-size: 0.92em;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--fg);
  cursor: pointer;
  transition: background 120ms ease, border-color 120ms ease;
}
.btn:hover { text-decoration: none; background: var(--bg-soft); }
.btn-primary {
  background: var(--primary);
  border-color: var(--primary);
  color: var(--primary-fg);
}
.btn-primary:hover { background: hsl(226, 81%, 30%); border-color: hsl(226, 81%, 30%); }

/* ── Hero (index only) ─────────────────────────────────────────────────── */

.hero {
  background: linear-gradient(180deg, var(--primary-soft) 0%, var(--bg) 100%);
  border-bottom: 1px solid var(--border-soft);
}
.hero-inner {
  max-width: var(--max-page);
  margin: 0 auto;
  padding: 64px 24px 48px;
  text-align: center;
}
.hero h1 {
  margin: 0 0 8px;
  font-size: 2.5rem;
  letter-spacing: -0.02em;
  font-weight: 700;
  color: var(--fg);
}
.hero p {
  margin: 0 auto;
  max-width: 580px;
  color: var(--fg-soft);
  font-size: 1.1rem;
}

/* ── Index — section grid ──────────────────────────────────────────────── */

.sections {
  max-width: var(--max-page);
  margin: 0 auto;
  padding: 48px 24px 96px;
}
.section + .section { margin-top: 48px; }
.section-title {
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--primary);
  margin: 0 0 16px;
}
.cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 14px;
}
.card {
  display: block;
  padding: 18px 20px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg);
  color: var(--fg);
  transition: border-color 120ms ease, box-shadow 120ms ease, transform 120ms ease;
}
.card:hover {
  border-color: var(--primary);
  box-shadow: var(--shadow-sm);
  text-decoration: none;
  transform: translateY(-1px);
}
.card-title {
  font-weight: 600;
  font-size: 1.02rem;
  margin: 0 0 4px;
  color: var(--fg);
}
.card-desc {
  margin: 0;
  font-size: 0.92rem;
  color: var(--fg-muted);
  line-height: 1.5;
}

/* ── Article layout ────────────────────────────────────────────────────── */

.article-page {
  max-width: var(--max-page);
  margin: 0 auto;
  padding: 32px 24px 96px;
  display: grid;
  grid-template-columns: 240px 1fr;
  gap: 56px;
}
.sidebar {
  position: sticky;
  top: 80px;
  align-self: start;
  font-size: 0.92rem;
  border-right: 1px solid var(--border-soft);
  padding-right: 16px;
  max-height: calc(100vh - 100px);
  overflow-y: auto;
}
.sidebar-section {
  margin-bottom: 22px;
}
.sidebar-title {
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--fg-muted);
  margin: 0 0 8px;
}
.sidebar ul {
  list-style: none;
  padding: 0;
  margin: 0;
}
.sidebar li {
  margin: 0;
}
.sidebar a {
  display: block;
  padding: 5px 8px;
  border-radius: 4px;
  color: var(--fg-soft);
}
.sidebar a:hover {
  background: var(--bg-soft);
  color: var(--fg);
  text-decoration: none;
}
.sidebar a.active {
  background: var(--primary-soft);
  color: var(--primary);
  font-weight: 500;
}

.article {
  max-width: var(--max-content);
  min-width: 0;
}
.crumbs {
  font-size: 0.85rem;
  color: var(--fg-muted);
  margin: 0 0 16px;
}
.crumbs a { color: var(--fg-muted); }
.crumbs a:hover { color: var(--primary); }

.article h1 {
  font-size: 2.05rem;
  letter-spacing: -0.015em;
  font-weight: 700;
  margin: 0 0 8px;
  line-height: 1.2;
}
.article .lead {
  color: var(--fg-soft);
  font-size: 1.08rem;
  margin: 0 0 32px;
}
.article h2 {
  font-size: 1.35rem;
  font-weight: 700;
  margin: 40px 0 12px;
  letter-spacing: -0.01em;
}
.article h3 {
  font-size: 1.08rem;
  font-weight: 600;
  margin: 24px 0 8px;
}
.article p {
  margin: 0 0 14px;
}
.article ul, .article ol {
  padding-left: 22px;
  margin: 0 0 14px;
}
.article li { margin-bottom: 6px; }

.callout {
  display: flex;
  gap: 12px;
  padding: 14px 16px;
  border: 1px solid var(--border);
  background: var(--bg-soft);
  border-radius: var(--radius-sm);
  margin: 16px 0;
}
.callout .icon {
  flex-shrink: 0;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  background: var(--primary);
  color: var(--primary-fg);
  font-weight: 700;
  font-size: 0.78rem;
  line-height: 22px;
  text-align: center;
}
.callout p { margin: 0; font-size: 0.94rem; }
.callout.warn { background: #fffaf0; border-color: #f4d8a8; }
.callout.warn .icon { background: #b76b00; }
.callout.success { background: #f1faf3; border-color: #c8e6cf; }
.callout.success .icon { background: #1f7a3a; }

table {
  width: 100%;
  border-collapse: collapse;
  margin: 16px 0;
  font-size: 0.94rem;
}
th, td {
  text-align: left;
  padding: 10px 12px;
  border-bottom: 1px solid var(--border);
}
th {
  background: var(--bg-soft);
  font-weight: 600;
  color: var(--fg-soft);
}

.next-prev {
  margin-top: 56px;
  padding-top: 24px;
  border-top: 1px solid var(--border-soft);
  display: flex;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}
.next-prev .np {
  flex: 1 1 240px;
  padding: 14px 16px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg);
  display: block;
  color: var(--fg);
  transition: border-color 120ms;
}
.next-prev .np:hover { border-color: var(--primary); text-decoration: none; }
.next-prev .np-label {
  display: block;
  font-size: 0.74rem;
  color: var(--fg-muted);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-bottom: 2px;
}
.next-prev .np.next { text-align: right; }

/* ── Footer ────────────────────────────────────────────────────────────── */

.site-footer {
  border-top: 1px solid var(--border-soft);
  padding: 28px 24px;
  text-align: center;
  color: var(--fg-muted);
  font-size: 0.88rem;
  background: var(--bg-soft);
}
.site-footer a { color: var(--fg-muted); }

/* ── Responsive ────────────────────────────────────────────────────────── */

@media (max-width: 880px) {
  .article-page {
    grid-template-columns: 1fr;
    gap: 24px;
  }
  .sidebar {
    position: static;
    border-right: none;
    border-bottom: 1px solid var(--border-soft);
    padding-right: 0;
    padding-bottom: 16px;
    max-height: none;
  }
  .hero-inner { padding: 44px 24px 32px; }
  .hero h1 { font-size: 1.95rem; }
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg:           #0e1117;
    --bg-soft:      #161a22;
    --bg-muted:     #1d2230;
    --border:       #262b39;
    --border-soft:  #1d2230;
    --fg:           #e6e9f0;
    --fg-soft:      #b6bccd;
    --fg-muted:     #8a92a5;
    --primary:      hsl(226, 81%, 70%);
    --primary-soft: hsl(226, 60%, 18%);
    --primary-fg:   #0e1117;
    --link:         hsl(226, 81%, 75%);
    --code-bg:      #1d2230;
  }
  .site-header { background: rgba(14, 17, 23, 0.85); }
  .callout.warn { background: rgba(183, 107, 0, 0.12); border-color: rgba(244, 216, 168, 0.3); }
  .callout.success { background: rgba(31, 122, 58, 0.12); border-color: rgba(200, 230, 207, 0.3); }
}