:root {
  color-scheme: dark;
  --measure: 64rem;

  --ink: #e7e3da;
  --ink-soft: #b7b2a7;
  --ink-faint: #8b877d;
  --paper: #16161a;
  --paper-2: #1e1e24;
  --paper-3: #25252d;
  --rule: #33333c;

  --accent: #ff6b6b;
  --accent-2: #56c7c7;
  --code-bg: #1e1e24;
  --code-ink: #ff9d9d;

  --ok: #7fd6a0;
  --ok-bg: #16281d;
  --warn: #e6c072;
  --warn-bg: #2a2312;
  --key-bg: #17232a;
  --key-border: #56c7c7;

  --shadow: 0 1px 2px rgba(0, 0, 0, 0.3), 0 4px 14px rgba(0, 0, 0, 0.4);
  --serif:
    "Iowan Old Style", "Palatino Linotype", Palatino, "Book Antiqua", Georgia,
    serif;
  --sans:
    -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial,
    sans-serif;
  --mono:
    "SF Mono", "JetBrains Mono", "Fira Code", ui-monospace, Menlo, Consolas,
    monospace;
}

@media (prefers-color-scheme: light) {
  :root {
    color-scheme: light;
    --ink: #1a1a1a;
    --ink-soft: #4a4a4a;
    --ink-faint: #767676;
    --paper: #fdfcf9;
    --paper-2: #f4f1ea;
    --paper-3: #faf7f0;
    --rule: #e2ddd2;
    --accent: #b21e1e;
    --accent-2: #1f6f6f;
    --code-bg: #f4f1ea;
    --code-ink: #6a1b1b;
    --ok: #1c6b3c;
    --ok-bg: #e9f5ec;
    --warn: #8a5a00;
    --warn-bg: #fbf1dc;
    --key-bg: #eef3f3;
    --key-border: #1f6f6f;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.05), 0 4px 14px rgba(0, 0, 0, 0.05);
  }
}

:root[data-theme="dark"] {
  color-scheme: dark;
}

:root[data-theme="light"] {
  color-scheme: light;
}

* {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  padding: 0 1.4rem 6rem;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 1.08rem;
  line-height: 1.62;
  letter-spacing: 0.1px;
}

a {
  color: var(--accent-2);
  text-decoration: none;
  border-bottom: 1px solid color-mix(in srgb, var(--accent-2) 35%, transparent);
}

a:hover {
  border-bottom-color: var(--accent-2);
}

.topbar {
  max-width: var(--measure);
  margin: 0 auto;
  padding: 1.5rem 0 0.6rem;
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 1rem;
  font-family: var(--sans);
  font-size: 0.82rem;
  border-bottom: 1px solid var(--rule);
}

.topbar a {
  color: var(--ink-faint);
  text-decoration: none;
  border: 0;
}

.topbar a:hover {
  color: var(--accent-2);
}

.crumbs {
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.wrap {
  max-width: var(--measure);
  margin: 0 auto;
}

h1,
h2,
h3 {
  font-family: var(--sans);
  line-height: 1.22;
  color: var(--ink);
}

h1 {
  font-size: 2.45rem;
  font-weight: 800;
  letter-spacing: -0.6px;
  margin: 2.2rem 0 0.3rem;
  max-width: 13ch;
}

h2 {
  font-size: 1.45rem;
  font-weight: 700;
  margin: 2.6rem 0 0.5rem;
  padding-top: 0.4rem;
}

h3 {
  font-size: 1.04rem;
  font-weight: 700;
  margin: 0 0 0.3rem;
  color: var(--ink);
}

p {
  margin: 0.7rem 0;
}

.eyebrow {
  font-family: var(--sans);
  font-size: 0.74rem;
  font-weight: 700;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent);
  margin: 2rem 0 0;
}

.subtitle {
  font-family: var(--serif);
  font-style: italic;
  font-size: 1.18rem;
  color: var(--ink-soft);
  margin: 0.1rem 0 1.6rem;
  max-width: 54rem;
}

.cite,
.lessons {
  color: var(--ink-faint);
}

.cite {
  margin: 0 0 1rem;
}

code {
  font-family: var(--mono);
  font-size: 0.86em;
  background: var(--code-bg);
  color: var(--code-ink);
  padding: 0.1em 0.38em;
  border-radius: 4px;
}

.callout,
.ask-teacher {
  border-left: 3px solid var(--rule);
  background: var(--paper-2);
  border-radius: 0 8px 8px 0;
  padding: 0.85rem 1.1rem;
  margin: 1.3rem 0;
  font-size: 1rem;
}

.callout .label {
  font-family: var(--sans);
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  display: block;
  margin-bottom: 0.25rem;
}

.callout.key {
  background: var(--key-bg);
  border-left-color: var(--key-border);
}

.callout.key .label {
  color: var(--key-border);
}

.callout.note {
  background: var(--paper-2);
  border-left-color: var(--ink-faint);
}

.callout.note .label {
  color: var(--ink-faint);
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1rem;
  margin: 1.4rem 0;
}

.card {
  display: block;
  background: linear-gradient(180deg, var(--paper-2), var(--paper-3));
  border: 1px solid var(--rule);
  border-radius: 10px;
  padding: 1rem 1.1rem;
  box-shadow: var(--shadow);
  transition:
    transform 160ms ease,
    border-color 160ms ease,
    box-shadow 160ms ease;
}

.card:hover,
.card:focus-visible {
  transform: translateY(-2px);
  border-color: color-mix(in srgb, var(--accent-2) 45%, var(--rule));
}

.card p,
.ask-teacher {
  margin: 0;
}

.meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  margin-bottom: 0.7rem;
}

.pill {
  display: inline-flex;
  align-items: center;
  border-radius: 999px;
  border: 1px solid color-mix(in srgb, var(--accent-2) 40%, transparent);
  background: color-mix(in srgb, var(--key-bg) 82%, transparent);
  color: var(--accent-2);
  font-family: var(--sans);
  font-size: 0.76rem;
  font-weight: 700;
  padding: 0.2rem 0.58rem;
}

.compact .card {
  padding: 0.95rem;
}

.ask-teacher {
  margin-top: 2rem;
  background: var(--paper-2);
  border-left-color: var(--ok);
}

@media (max-width: 720px) {
  body {
    padding: 0 1rem 4rem;
  }

  .topbar {
    flex-direction: column;
    align-items: flex-start;
  }

  h1 {
    font-size: 2rem;
    max-width: none;
  }
}