/* ===========================================================================
   course.css — the one stylesheet every lesson and reference doc links.
   Lessons are read weeks later on a different screen; typography and rhythm
   matter more than novelty. Tufte-adjacent: generous leading, a real measure,
   colour used only where it carries meaning.
   =========================================================================== */

:root {
  --ink: #1a1a1a;
  --ink-soft: #4a4a4a;
  --ink-faint: #767676;
  --paper: #fdfdfc;
  --rule: #e2e0da;
  --rule-soft: #efedE7;
  --accent: #1f5c8b;
  --accent-soft: #e8f0f6;
  --warn: #9a3412;
  --warn-soft: #fdf1e7;
  --good: #14532d;
  --good-soft: #eaf3ed;
  --bad: #7f1d1d;
  --bad-soft: #fbeaea;
  --mono: ui-monospace, "SF Mono", "Cascadia Code", Menlo, Consolas, monospace;
  --serif: "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, serif;
  --sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  --measure: 34rem;
}

@media (prefers-color-scheme: dark) {
  :root {
    --ink: #e8e6e1;
    --ink-soft: #b8b5ae;
    --ink-faint: #8b8880;
    --paper: #16171a;
    --rule: #2e3036;
    --rule-soft: #232529;
    --accent: #7fb4dc;
    --accent-soft: #1b2a36;
    --warn: #e8a87c;
    --warn-soft: #2e2118;
    --good: #86c9a0;
    --good-soft: #16261c;
    --bad: #e08b8b;
    --bad-soft: #2c1a1a;
  }
}

* { box-sizing: border-box; }

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

body {
  margin: 0;
  padding: 3.5rem 1.25rem 6rem;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 1.0625rem;
  line-height: 1.65;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

/* ---- measure & masthead -------------------------------------------------- */

.wrap { max-width: var(--measure); margin: 0 auto; }
.wrap-wide { max-width: 48rem; margin: 0 auto; }

.masthead {
  border-bottom: 1px solid var(--rule);
  padding-bottom: 1.25rem;
  margin-bottom: 2.5rem;
}

.kicker {
  font-family: var(--mono);
  font-size: 0.6875rem;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--ink-faint);
  margin: 0 0 0.6rem;
}

h1 {
  font-size: 2rem;
  line-height: 1.18;
  letter-spacing: -0.017em;
  font-weight: 700;
  margin: 0 0 0.5rem;
  color: var(--ink);
}

.standfirst {
  font-size: 1.125rem;
  line-height: 1.55;
  color: var(--ink-soft);
  margin: 0;
  font-style: italic;
}

h2 {
  font-size: 1.3rem;
  line-height: 1.3;
  letter-spacing: -0.01em;
  font-weight: 700;
  margin: 3rem 0 0.85rem;
  padding-bottom: 0.3rem;
  border-bottom: 1px solid var(--rule-soft);
}

h3 {
  font-size: 1.0625rem;
  font-weight: 700;
  margin: 1.9rem 0 0.5rem;
  color: var(--ink);
}

h4 {
  font-family: var(--mono);
  font-size: 0.75rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink-faint);
  margin: 1.5rem 0 0.4rem;
  font-weight: 600;
}

p { margin: 0 0 1.05rem; }
p:last-child { margin-bottom: 0; }

a {
  color: var(--accent);
  text-decoration-color: color-mix(in srgb, var(--accent) 35%, transparent);
  text-underline-offset: 2px;
}
a:hover { text-decoration-color: var(--accent); }

strong { font-weight: 700; }
em { font-style: italic; }

ul, ol { margin: 0 0 1.05rem; padding-left: 1.35rem; }
li { margin-bottom: 0.4rem; }
li:last-child { margin-bottom: 0; }

/* ---- code --------------------------------------------------------------- */

code {
  font-family: var(--mono);
  font-size: 0.8125em;
  background: var(--rule-soft);
  padding: 0.12em 0.35em;
  border-radius: 3px;
  word-break: break-word;
}

pre {
  font-family: var(--mono);
  font-size: 0.78rem;
  line-height: 1.55;
  background: var(--rule-soft);
  border: 1px solid var(--rule);
  border-left: 2px solid var(--accent);
  border-radius: 4px;
  padding: 0.85rem 1rem;
  overflow-x: auto;
  margin: 0 0 1.15rem;
  color: var(--ink);
}
pre code { background: none; padding: 0; font-size: 1em; }

/* ---- callouts ----------------------------------------------------------- */

.note {
  border-left: 2px solid var(--accent);
  background: var(--accent-soft);
  padding: 0.85rem 1.1rem;
  margin: 0 0 1.3rem;
  border-radius: 0 4px 4px 0;
  font-size: 0.975rem;
}
.note > :last-child { margin-bottom: 0; }

.warn {
  border-left: 2px solid var(--warn);
  background: var(--warn-soft);
  padding: 0.85rem 1.1rem;
  margin: 0 0 1.3rem;
  border-radius: 0 4px 4px 0;
  font-size: 0.975rem;
}
.warn > :last-child { margin-bottom: 0; }

.good {
  border-left: 2px solid var(--good);
  background: var(--good-soft);
  padding: 0.85rem 1.1rem;
  margin: 0 0 1.3rem;
  border-radius: 0 4px 4px 0;
  font-size: 0.975rem;
}
.good > :last-child { margin-bottom: 0; }

/* ---- tables ------------------------------------------------------------- */

.table-scroll { overflow-x: auto; margin: 0 0 1.3rem; }

table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--sans);
  font-size: 0.8125rem;
  line-height: 1.45;
}

th {
  text-align: left;
  font-size: 0.6875rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink-faint);
  font-weight: 600;
  padding: 0.4rem 0.7rem 0.4rem 0;
  border-bottom: 1px solid var(--rule);
  white-space: nowrap;
}

td {
  padding: 0.5rem 0.7rem 0.5rem 0;
  border-bottom: 1px solid var(--rule-soft);
  vertical-align: top;
}
td:last-child, th:last-child { padding-right: 0; }

td code { font-size: 0.92em; }

/* ---- state badges ------------------------------------------------------- */

.badge {
  display: inline-block;
  font-family: var(--mono);
  font-size: 0.6875rem;
  letter-spacing: 0.03em;
  padding: 0.1rem 0.4rem;
  border-radius: 3px;
  font-weight: 600;
  white-space: nowrap;
  vertical-align: 1px;
}
.badge-real { background: var(--good-soft); color: var(--good); }
.badge-dead { background: var(--bad-soft); color: var(--bad); }
.badge-partial { background: var(--warn-soft); color: var(--warn); }

/* ---- quiz (see quiz.js) ------------------------------------------------- */

.quiz {
  border: 1px solid var(--rule);
  border-radius: 6px;
  padding: 1.1rem 1.2rem 1.2rem;
  margin: 0 0 1.6rem;
  background: var(--paper);
}

.quiz-q {
  font-family: var(--sans);
  font-size: 0.9375rem;
  font-weight: 600;
  line-height: 1.45;
  margin: 0 0 0.85rem;
}

.quiz-opts { display: grid; gap: 0.45rem; }

.quiz-opt {
  display: block;
  width: 100%;
  text-align: left;
  font-family: var(--sans);
  font-size: 0.875rem;
  line-height: 1.45;
  padding: 0.6rem 0.8rem;
  border: 1px solid var(--rule);
  border-radius: 5px;
  background: var(--paper);
  color: var(--ink-soft);
  cursor: pointer;
  transition: border-color 0.12s, background 0.12s, color 0.12s;
}
.quiz-opt:hover:not(:disabled) { border-color: var(--accent); color: var(--ink); }
.quiz-opt:disabled { cursor: default; }

.quiz-opt.correct {
  background: var(--good-soft);
  border-color: var(--good);
  color: var(--good);
  font-weight: 600;
}
.quiz-opt.wrong {
  background: var(--bad-soft);
  border-color: var(--bad);
  color: var(--bad);
}
.quiz-opt.reveal { border-color: var(--good); }

.quiz-why {
  margin-top: 0.85rem;
  padding-top: 0.75rem;
  border-top: 1px solid var(--rule-soft);
  font-family: var(--sans);
  font-size: 0.8125rem;
  line-height: 1.5;
  color: var(--ink-soft);
}
.quiz-why[hidden] { display: none; }
.quiz-why strong { color: var(--ink); }

/* ---- retrieval practice (recall before reveal) -------------------------- */

.recall { margin: 0 0 1.6rem; }

.recall summary {
  cursor: pointer;
  font-family: var(--sans);
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--accent);
  padding: 0.5rem 0;
  list-style: none;
  border-bottom: 1px dashed var(--rule);
}
.recall summary::-webkit-details-marker { display: none; }
.recall summary::before { content: "▸ "; color: var(--ink-faint); }
.recall[open] summary::before { content: "▾ "; }
.recall summary:hover { color: var(--ink); }

.recall-body {
  padding: 0.7rem 0 0.2rem;
  font-family: var(--sans);
  font-size: 0.875rem;
  line-height: 1.55;
  color: var(--ink-soft);
}
.recall-body > :last-child { margin-bottom: 0; }

/* ---- lists of checks ----------------------------------------------------- */

.checks { list-style: none; padding: 0; margin: 0 0 1.3rem; }
.checks li {
  padding-left: 1.5rem;
  position: relative;
  margin-bottom: 0.5rem;
  font-size: 0.975rem;
}
.checks li::before {
  content: "—";
  position: absolute;
  left: 0;
  color: var(--ink-faint);
}

/* ---- steps -------------------------------------------------------------- */

ol.steps { list-style: none; counter-reset: step; padding: 0; }
ol.steps > li {
  counter-increment: step;
  position: relative;
  padding-left: 2.1rem;
  margin-bottom: 0.9rem;
}
ol.steps > li::before {
  content: counter(step);
  position: absolute;
  left: 0;
  top: 0.05rem;
  width: 1.5rem;
  height: 1.5rem;
  border-radius: 50%;
  background: var(--accent-soft);
  color: var(--accent);
  font-family: var(--mono);
  font-size: 0.75rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* ---- footer / nav ------------------------------------------------------- */

.lesson-end {
  margin-top: 3.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--rule);
  font-family: var(--sans);
  font-size: 0.875rem;
  line-height: 1.6;
  color: var(--ink-soft);
}

.nav {
  display: flex;
  flex-wrap: wrap;
  gap: 1.25rem;
  margin: 2.5rem 0 0;
  padding-top: 1.25rem;
  border-top: 1px solid var(--rule);
  font-family: var(--sans);
  font-size: 0.8125rem;
}
.nav a { text-decoration: none; color: var(--accent); }
.nav a:hover { text-decoration: underline; }
.nav .spacer { flex: 1; }

.ask {
  background: var(--rule-soft);
  border-radius: 5px;
  padding: 0.9rem 1.1rem;
  margin: 1.5rem 0 0;
  font-size: 0.9375rem;
}
.ask > :last-child { margin-bottom: 0; }

/* ---- print -------------------------------------------------------------- */

@media print {
  :root {
    --paper: #fff; --ink: #000; --ink-soft: #333; --ink-faint: #666;
    --rule: #ccc; --rule-soft: #e5e5e5;
  }
  body { padding: 0; font-size: 10.5pt; background: #fff; }
  .quiz, .note, .warn, .good, pre, table { break-inside: avoid; }
  .quiz-opt { display: none; }
  .quiz-why[hidden] { display: block !important; }
  .recall[open] summary ~ .recall-body { display: block; }
  .recall-body { display: block !important; }
  .nav, .ask { display: none; }
  a { color: #000; text-decoration: underline; }
}

@media (max-width: 30rem) {
  body { padding: 2rem 1rem 4rem; font-size: 1rem; }
  h1 { font-size: 1.6rem; }
}