/* Shared stylesheet for all lessons and reference docs in this workspace.
   Tufte-inspired: generous margins, sidenotes, restrained palette, prints well. */

:root {
  --bg: #fffef9;
  --fg: #1a1a18;
  --muted: #6b6a63;
  --rule: #ddd9cc;
  --accent: #8a3a1e;
  --accent-soft: #f6ede6;
  --code-bg: #f4f1e8;
  --ok: #2c6e49;
  --warn: #9a6700;
  --measure: 38rem;
  --font-body: "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, serif;
  --font-mono: "SF Mono", "JetBrains Mono", Menlo, Consolas, monospace;
  --font-sans: -apple-system, "Segoe UI", Inter, system-ui, sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #16161a;
    --fg: #e6e3dc;
    --muted: #94918a;
    --rule: #35353c;
    --accent: #e0855f;
    --accent-soft: #2a211c;
    --code-bg: #202026;
    --ok: #6fbf8f;
    --warn: #d3a95c;
  }
}

* { box-sizing: border-box; }

body {
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font-body);
  font-size: 1.05rem;
  line-height: 1.6;
  margin: 0;
  padding: 3rem 1.5rem 6rem;
  -webkit-font-smoothing: antialiased;
}

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

/* ---- Masthead ---- */

.masthead {
  border-bottom: 1px solid var(--rule);
  padding-bottom: 1.25rem;
  margin-bottom: 2.5rem;
}
.eyebrow {
  font-family: var(--font-sans);
  font-size: 0.7rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0 0 0.5rem;
}
.masthead h1 {
  font-size: 2rem;
  line-height: 1.2;
  font-weight: 600;
  margin: 0 0 0.6rem;
  letter-spacing: -0.01em;
}
.deck {
  color: var(--muted);
  font-size: 1.05rem;
  font-style: italic;
  margin: 0;
}

/* ---- Type ---- */

h2 {
  font-size: 1.3rem;
  font-weight: 600;
  margin: 3rem 0 1rem;
  letter-spacing: -0.005em;
}
h3 {
  font-family: var(--font-sans);
  font-size: 0.82rem;
  font-weight: 650;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 2rem 0 0.75rem;
}
p { margin: 0 0 1.1rem; }
a { color: var(--accent); text-decoration: none; border-bottom: 1px solid var(--rule); }
a:hover { border-bottom-color: var(--accent); }
strong { font-weight: 650; }
ul, ol { padding-left: 1.3rem; margin: 0 0 1.1rem; }
li { margin-bottom: 0.5rem; }
code {
  font-family: var(--font-mono);
  font-size: 0.85em;
  background: var(--code-bg);
  padding: 0.12em 0.35em;
  border-radius: 3px;
}
pre {
  background: var(--code-bg);
  border-left: 2px solid var(--rule);
  padding: 1rem 1.1rem;
  overflow-x: auto;
  font-size: 0.82rem;
  line-height: 1.55;
  border-radius: 0 4px 4px 0;
}
pre code { background: none; padding: 0; font-size: inherit; }

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

.epigraph {
  border-left: 2px solid var(--accent);
  padding: 0.2rem 0 0.2rem 1.2rem;
  margin: 2rem 0;
  font-style: italic;
  color: var(--muted);
}
.epigraph cite {
  display: block;
  font-style: normal;
  font-family: var(--font-sans);
  font-size: 0.78rem;
  margin-top: 0.5rem;
}

.note {
  background: var(--accent-soft);
  border-radius: 5px;
  padding: 1rem 1.2rem;
  margin: 1.75rem 0;
  font-size: 0.95rem;
}
.note p:last-child { margin-bottom: 0; }
.note .label {
  display: block;
  font-family: var(--font-sans);
  font-size: 0.68rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent);
  font-weight: 650;
  margin-bottom: 0.4rem;
}

/* ---- Tables ---- */

.table-wrap { overflow-x: auto; margin: 1.75rem 0; }
table {
  border-collapse: collapse;
  width: 100%;
  font-family: var(--font-sans);
  font-size: 0.85rem;
}
th, td {
  text-align: left;
  padding: 0.55rem 0.8rem 0.55rem 0;
  border-bottom: 1px solid var(--rule);
  vertical-align: top;
}
th {
  font-weight: 650;
  font-size: 0.7rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
  border-bottom-width: 1.5px;
}

/* ---- Steps ---- */

.step {
  border-top: 1px solid var(--rule);
  padding-top: 1.25rem;
  margin-top: 2rem;
}
.step-num {
  font-family: var(--font-sans);
  font-size: 0.68rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent);
  font-weight: 650;
}
.step h2 { margin-top: 0.3rem; }

/* ---- Footer ---- */

.footer {
  margin-top: 4rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--rule);
  font-family: var(--font-sans);
  font-size: 0.85rem;
  color: var(--muted);
}
.footer h3 { margin-top: 0; }
.ask {
  background: var(--accent-soft);
  border-radius: 5px;
  padding: 0.9rem 1.1rem;
  margin-top: 1.5rem;
  color: var(--fg);
}

/* ---- Course index (index.html) ---- */

.toc { list-style: none; padding: 0; margin: 0; }
.toc li { margin: 0; }

.toc-item {
  display: flex;
  gap: 1.1rem;
  align-items: baseline;
  padding: 1.1rem 0.9rem 1.1rem 0.7rem;
  border-bottom: 1px solid var(--rule);
  border-radius: 4px;
  text-decoration: none;
  border-left: 2px solid transparent;
  color: inherit;
  transition: background 0.12s, border-left-color 0.12s;
}
a.toc-item:hover {
  background: var(--accent-soft);
  border-left-color: var(--accent);
}
.toc-num {
  font-family: var(--font-sans);
  font-size: 0.72rem;
  font-weight: 650;
  letter-spacing: 0.08em;
  color: var(--accent);
  flex: 0 0 2.4rem;
}
.toc-body { flex: 1; }
.toc-title { font-weight: 600; display: block; margin-bottom: 0.2rem; }
.toc-desc {
  display: block;
  font-family: var(--font-sans);
  font-size: 0.83rem;
  line-height: 1.45;
  color: var(--muted);
}
.toc-item.is-pending { opacity: 0.55; cursor: default; }
.toc-item.is-pending .toc-num { color: var(--muted); }
.tag {
  display: inline-block;
  font-family: var(--font-sans);
  font-size: 0.62rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  font-weight: 650;
  padding: 0.12rem 0.4rem;
  border-radius: 3px;
  border: 1px solid var(--rule);
  color: var(--muted);
  margin-left: 0.4rem;
  vertical-align: 0.1em;
}

/* ---- Interactive widgets (quiz.js, classify.js) ---- */

.quiz, .classify {
  display: block;
  border: 1px solid var(--rule);
  border-radius: 6px;
  padding: 1.4rem 1.5rem;
  margin: 2rem 0;
  background: var(--code-bg);
}
.quiz h3, .classify h3 { margin-top: 0; }

.quiz-q + .quiz-q { margin-top: 1.75rem; padding-top: 1.5rem; border-top: 1px solid var(--rule); }
.quiz-prompt { font-weight: 600; margin-bottom: 0.9rem; }
.quiz-options, .classify-labels { display: flex; flex-direction: column; gap: 0.5rem; }

.quiz-option, .classify-label {
  font-family: var(--font-sans);
  font-size: 0.88rem;
  text-align: left;
  padding: 0.6rem 0.85rem;
  border: 1px solid var(--rule);
  border-radius: 4px;
  background: var(--bg);
  color: var(--fg);
  cursor: pointer;
  transition: border-color 0.12s, background 0.12s;
}
.quiz-option:hover:not(:disabled), .classify-label:hover:not(:disabled) {
  border-color: var(--accent);
}
.quiz-option:disabled, .classify-label:disabled { cursor: default; opacity: 0.75; }
.is-correct {
  border-color: var(--ok) !important;
  box-shadow: inset 3px 0 0 var(--ok);
  opacity: 1 !important;
  font-weight: 600;
}
.is-wrong {
  border-color: var(--accent) !important;
  box-shadow: inset 3px 0 0 var(--accent);
  opacity: 1 !important;
  text-decoration: line-through;
}

.quiz-why, .classify-why {
  font-family: var(--font-sans);
  font-size: 0.85rem;
  line-height: 1.5;
  margin: 0.9rem 0 0;
  padding-left: 0.85rem;
  border-left: 2px solid var(--rule);
  color: var(--muted);
}
.quiz-why.was-right { border-left-color: var(--ok); }
.quiz-why.was-wrong { border-left-color: var(--accent); }

.classify-score {
  font-family: var(--font-sans);
  font-size: 0.78rem;
  color: var(--muted);
  margin: -0.4rem 0 1.2rem;
}
.classify-card + .classify-card { margin-top: 1.75rem; padding-top: 1.5rem; border-top: 1px solid var(--rule); }
.classify-trace {
  background: var(--bg);
  border-left: 2px solid var(--muted);
  font-size: 0.78rem;
  white-space: pre-wrap;
  margin: 0 0 0.9rem;
}

/* ---- Print ---- */

@media print {
  :root { --bg: #fff; --fg: #000; }
  body { padding: 0; font-size: 11pt; }
  .quiz, .ask { break-inside: avoid; }
  a { color: #000; border: none; }
  a[href^="http"]::after {
    content: " (" attr(href) ")";
    font-size: 0.7em;
    color: #555;
    word-break: break-all;
  }
}