:root {
  --bg: oklch(98.5% 0.003 240);
  --bg-raised: oklch(96% 0.004 240);
  --fg: oklch(22% 0.01 250);
  --muted: oklch(48% 0.012 250);
  --border: oklch(88% 0.006 240);
  --accent: oklch(52% 0.14 200);
  --accent-fg: oklch(99% 0.003 240);
  --code-bg: oklch(96% 0.004 240);
  --code-border: oklch(90% 0.006 240);

  --accepted-fg: oklch(40% 0.13 145);
  --accepted-bg: oklch(94% 0.045 145);
  --rejected-fg: oklch(46% 0.16 25);
  --rejected-bg: oklch(94.5% 0.045 25);
  --pending-fg: oklch(42% 0.1 80);
  --pending-bg: oklch(93.5% 0.05 80);
  --unchecked-fg: var(--muted);
  --unchecked-bg: var(--bg-raised);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: oklch(21% 0.006 250);
    --bg-raised: oklch(26% 0.009 250);
    --fg: oklch(92% 0.004 250);
    --muted: oklch(68% 0.012 250);
    --border: oklch(35% 0.012 250);
    --accent: oklch(76% 0.12 200);
    --accent-fg: oklch(15% 0.01 250);
    --code-bg: oklch(26% 0.009 250);
    --code-border: oklch(32% 0.01 250);

    --accepted-fg: oklch(80% 0.13 145);
    --accepted-bg: oklch(27% 0.05 145);
    --rejected-fg: oklch(80% 0.14 25);
    --rejected-bg: oklch(28% 0.055 25);
    --pending-fg: oklch(82% 0.1 80);
    --pending-bg: oklch(27% 0.05 80);
    --unchecked-fg: var(--muted);
    --unchecked-bg: var(--bg-raised);
  }
}

* {
  box-sizing: border-box;
}

html {
  text-wrap: pretty;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: Georgia, "Times New Roman", serif;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 {
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  font-weight: 700;
  letter-spacing: -0.01em;
}

code, pre, kbd {
  font-family: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
  font-size: 0.88em;
}

a {
  color: var(--accent);
  text-decoration-thickness: 1px;
}
a:hover {
  color: var(--accent);
  text-decoration-thickness: 2px;
}

/* --- sidebar home link --- */

.sidebar-home {
  display: block;
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  font-weight: 700;
  font-size: 1rem;
  color: var(--fg);
  text-decoration: none;
  margin-bottom: 1rem;
}
.sidebar-home:hover {
  color: var(--accent);
}

/* --- landing page --- */

main.landing {
  max-width: 62ch;
  margin: 0 auto;
  padding: 4rem 1.5rem 5rem;
}

main.landing h1 {
  font-size: 3rem;
  margin: 0 0 0.4rem;
}

.tagline {
  color: var(--muted);
  font-size: 1.2rem;
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  max-width: 42ch;
}

main.landing > p {
  font-size: 1.05rem;
}

.landing-links {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 0.75rem;
  margin-top: 2.5rem;
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
}

.landing-links a {
  display: block;
  padding: 1rem 1.1rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  text-decoration: none;
  color: var(--fg);
  font-size: 0.98rem;
  font-weight: 600;
  transition: border-color 0.15s ease;
}
.landing-links a:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* --- page shell with sidebar --- */

.page-shell {
  display: flex;
  align-items: flex-start;
  max-width: 90rem;
  margin: 0 auto;
}

.sidebar-toggle-input {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

.sidebar {
  flex: 0 0 auto;
}

.sidebar-toggle-label {
  display: block;
  cursor: pointer;
  padding: 0.75rem 1.5rem;
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--muted);
  border-bottom: 1px solid var(--border);
}
.sidebar-toggle-label::before {
  content: "☰ Chapters";
}
.sidebar-toggle-input:checked ~ .sidebar-toggle-label::before {
  content: "▾ Chapters";
}

.sidebar-inner {
  padding: 1.25rem 1.5rem 2rem;
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  font-size: 0.85rem;
}

.sidebar-label {
  display: block;
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin: 1.25rem 0 0.5rem;
}
.sidebar-label:first-child {
  margin-top: 0;
}

.sidebar-inner ul {
  list-style: none;
  margin: 0;
  padding: 0;
}
.sidebar-inner li {
  margin: 0.15rem 0;
}
.sidebar-inner li.nested {
  padding-left: 0.85rem;
}
.sidebar-inner a {
  display: block;
  padding: 0.2rem 0;
  text-decoration: none;
  color: var(--muted);
  line-height: 1.4;
}
.sidebar-inner a:hover {
  color: var(--accent);
}
.sidebar-inner a.current {
  color: var(--accent);
  font-weight: 600;
}

main.chapter {
  flex: 1 1 auto;
  min-width: 0;
  max-width: 72ch;
  margin: 0 auto;
  padding: 2.5rem 1.5rem 5rem;
}

.sidebar-inner {
  display: none;
}
.sidebar-toggle-input:checked ~ .sidebar-inner {
  display: block;
}

@media (min-width: 900px) {
  .sidebar {
    width: 240px;
    position: sticky;
    top: 0;
    max-height: 100vh;
    overflow-y: auto;
    border-right: 1px solid var(--border);
  }
  .sidebar-toggle-label {
    display: none;
  }
  .sidebar-inner {
    display: block !important;
  }
}

/* --- chapter content --- */

main.chapter h1 {
  font-size: 2rem;
}

main.chapter h1,
main.chapter h2,
main.chapter h3 {
  scroll-margin-top: 1rem;
}

main.chapter h2 {
  margin-top: 2.75rem;
  padding-top: 0.5rem;
  border-top: 1px solid var(--border);
}

main.chapter table {
  border-collapse: collapse;
  width: 100%;
  margin: 1.5rem 0;
  font-size: 0.95rem;
}

main.chapter th,
main.chapter td {
  border-bottom: 1px solid var(--border);
  padding: 0.55rem 0.7rem;
  text-align: left;
  vertical-align: top;
}

main.chapter th {
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--muted);
  border-bottom: 2px solid var(--border);
}

main.chapter pre {
  background: var(--code-bg);
  border: 1px solid var(--code-border);
  padding: 0.85rem 1rem;
  overflow-x: auto;
  overflow-y: hidden;
  border-radius: 6px;
  margin: 1rem 0;
  line-height: 1.55;
}

main.chapter :not(pre) > code {
  background: var(--code-bg);
  border: 1px solid var(--code-border);
  padding: 0.1em 0.35em;
  border-radius: 4px;
}

/* --- zel-block callouts --- */

.zel-block {
  margin: 1.5rem 0;
  border: 1px solid var(--border);
  border-radius: 6px;
  overflow: hidden;
}

main.chapter .zel-block pre {
  margin: 0;
  border: none;
  border-radius: 0;
  border-top: 1px solid var(--border);
  overflow-y: hidden;
}

.zel-block-tags {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.55rem 1rem;
  font-size: 0.76rem;
  font-family: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
}

.zel-tag,
.zel-package {
  display: inline-flex;
  align-items: center;
  gap: 0.35em;
  padding: 0.1rem 0.55rem;
  border-radius: 999px;
  font-weight: 600;
}

.zel-tag::before {
  content: "";
  width: 0.5em;
  height: 0.5em;
  border-radius: 50%;
  background: currentColor;
}

.zel-package {
  background: var(--unchecked-bg);
  color: var(--muted);
  font-weight: 400;
}

.expect-accepted .zel-tag {
  background: var(--accepted-bg);
  color: var(--accepted-fg);
}
.expect-rejected .zel-tag {
  background: var(--rejected-bg);
  color: var(--rejected-fg);
}
.expect-pending .zel-tag {
  background: var(--pending-bg);
  color: var(--pending-fg);
}
.expect-unchecked {
  border-style: dashed;
}
.expect-unchecked .zel-tag {
  background: var(--unchecked-bg);
  color: var(--unchecked-fg);
}