/* Shared stylesheet for all lessons and reference docs. Quiet, humanist sans, generous size.
   Dark by default; the print block below swaps back to ink-on-paper. */

:root {
  --ink: #e4e1d9;
  --paper: #15171b;
  --muted: #9b978d;
  --rule: #2f333a;
  --panel: #1d2025;
  --panel-hover: #24282e;
  --accent: #e3a172;
  --good: #74c48a;
  --good-bg: #172a1d;
  --bad: #e8796e;
  --bad-bg: #2b1715;
  color-scheme: dark;
}

* { box-sizing: border-box; }

body {
  max-width: 40em;
  margin: 3rem auto 6rem;
  padding: 0 1.5rem;
  background: var(--paper);
  color: var(--ink);
  font-family: "Inter", "Ubuntu Sans", Ubuntu, system-ui, "Segoe UI", -apple-system,
               "Noto Sans", "DejaVu Sans", sans-serif;
  font-size: 1.2rem;
  line-height: 1.68;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3 {
  font-weight: 600;
  line-height: 1.25;
}

h1 { font-size: 2.1rem; margin-bottom: 0.2rem; letter-spacing: -0.01em; }
h1 + .subtitle { color: var(--muted); font-size: 1.02rem; margin-top: 0; margin-bottom: 2rem; }

h2 { font-size: 1.45rem; margin-top: 2.5rem; border-top: 1px solid var(--rule); padding-top: 1.5rem; }

a { color: var(--accent); text-decoration: underline dotted; text-underline-offset: 2px; }
a:hover { text-decoration-style: solid; }

code, pre {
  font-family: "JetBrains Mono", "Cascadia Mono", "DejaVu Sans Mono",
               "Ubuntu Sans Mono", Consolas, Menlo, monospace;
  font-size: 0.87em;
  font-variant-ligatures: none;
}

pre {
  background: var(--panel);
  /* Smaller than inline code, so long rustc output overflows by as little as possible.
     Wrapping is not an option: the `^^^^` underlines must stay column-aligned or they
     point at the wrong token. Blocks that still exceed the column scroll sideways. */
  font-size: 0.73em;
  line-height: 1.5;
  border: 1px solid var(--rule);
  border-radius: 4px;
  padding: 0.9em 1em;
  overflow-x: auto;
}

code { background: var(--panel); padding: 0.1em 0.3em; border-radius: 3px; }
pre code { background: none; padding: 0; font-size: 1em; }   /* no compounding */

.cite {
  font-size: 0.85em;
  color: var(--muted);
  border-left: 2px solid var(--rule);
  padding-left: 0.7em;
  margin: 0.5em 0 0;
}

.callout {
  border: 1px solid var(--rule);
  background: var(--panel);
  border-radius: 6px;
  padding: 1em 1.2em;
  margin: 1.5rem 0;
  font-size: 0.95em;
}

/* Quoted primary sources — verbatim text from the book, std docs, or guidelines */
blockquote {
  margin: 1.5rem 0 0.4rem;
  padding: 0.2em 0 0.2em 1.1em;
  border-left: 3px solid var(--accent);
  color: var(--ink);
  font-size: 0.97em;
}
blockquote p { margin: 0.4em 0; }
blockquote + .cite { margin-top: 0; }

/* Coverage tables: a cell that names a real gap */
.gap { color: var(--bad); font-weight: 600; }

/* Quiz widget */
.q {
  border-top: 1px solid var(--rule);
  padding: 1.4rem 0;
}

.q .topic {
  display: inline-block;
  font-size: 0.75rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 0.4em;
}

.q .prompt { margin: 0 0 0.8em; }

.q button {
  font-family: inherit;
  color: inherit;
  font-size: 0.92rem;
  background: transparent;
  border: 1px solid var(--rule);
  border-radius: 4px;
  padding: 0.35em 0.8em;
  cursor: pointer;
  margin: 0.2em 0.4em 0.2em 0;
}
.q button:hover:not(:disabled) { background: var(--panel-hover); }
.q button:disabled { cursor: default; }

.options { display: flex; flex-direction: column; align-items: flex-start; }
.opt { text-align: left; width: 100%; }
.opt.correct, .grade button.opt-correct { border-color: var(--good); background: var(--good-bg); color: var(--good); }
.opt.incorrect, .grade button.opt-incorrect { border-color: var(--bad); background: var(--bad-bg); color: var(--bad); }
.q button:disabled { opacity: 1; }
.grade button:disabled:not(.opt-correct):not(.opt-incorrect) { opacity: 0.45; }

.answer, .explain {
  background: var(--panel);
  border-left: 3px solid var(--accent);
  padding: 0.7em 1em;
  margin-top: 0.6em;
}

.grade button[data-grade="hit"]:hover { border-color: var(--good); }
.grade button[data-grade="miss"]:hover { border-color: var(--bad); }

.hidden { display: none !important; }

#summary {
  margin-top: 2.5rem;
  border-top: 2px solid var(--ink);
  padding-top: 1rem;
}
#summary-body { white-space: pre-line; }
#report-output {
  white-space: pre-line;
  background: var(--panel);
  padding: 0.8em 1em;
  border-radius: 4px;
  margin-top: 0.8em;
}

/* Collapsible hints */
details {
  border: 1px solid var(--rule);
  border-radius: 6px;
  padding: 0.6em 1em;
  margin: 0.7rem 0;
  background: var(--panel);
}
details[open] { background: var(--panel-hover); }
summary {
  cursor: pointer;
  font-weight: 600;
  color: var(--accent);
}
details > *:last-child { margin-bottom: 0; }

/* Spec tables */
table {
  border-collapse: collapse;
  width: 100%;
  margin: 1rem 0;
  font-size: 0.95em;
}
th, td {
  border-bottom: 1px solid var(--rule);
  padding: 0.4em 0.6em;
  text-align: left;
  vertical-align: top;
}
th { border-bottom: 2px solid var(--ink); }

footer {
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--rule);
  color: var(--muted);
  font-size: 0.9rem;
}

@media print {
  :root {
    --ink: #1a1a1a;
    --paper: #fff;
    --muted: #555;
    --rule: #ccc;
    --panel: #f4f2ec;
    --panel-hover: #eeece5;
    --accent: #8a3324;
    --good: #2a7a3b;
    --good-bg: #eaf5ec;
    --bad: #a3312a;
    --bad-bg: #fbeceb;
    color-scheme: light;
  }
  body { margin: 0.5rem auto; }
  .hidden { display: block !important; }
  .q button, #report-btn { display: none !important; }
  pre { font-size: 0.62em; }   /* paper is narrower than a screen, and cannot scroll */
  pre, blockquote, table, .q { break-inside: avoid; }
}