/* Shared stylesheet for Data Visualization lessons & reference sheets. Tufte-ish: quiet, serif, generous margins. */

:root {
  --bg: #ffffff;
  --ink: #1a1a1a;
  --ink-soft: #4a4a45;
  --rule: #ddd8cc;
  --accent: #a5502c;
  --accent-soft: #f2e6da;
  --good: #2f6d3e;
  --good-bg: #e9f3ea;
  --bad: #a5342c;
  --bad-bg: #f8eae8;
  --code-bg: #f1efe6;
  --max-width: 720px;
}

* { box-sizing: border-box; }

html { background: var(--bg); }

body {
  background: var(--bg);
  color: var(--ink);
  font-family: "iowan old style", "Palatino Linotype", Palatino, Georgia, "Noto Serif Thai", serif;
  font-size: 19px;
  line-height: 1.55;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 3rem 1.5rem 6rem;
}

h1, h2, h3 {
  font-weight: 600;
  line-height: 1.25;
  color: var(--ink);
}

h1 {
  font-size: 2rem;
  margin: 0 0 0.3em;
}

.kicker {
  font-family: -apple-system, "Helvetica Neue", Arial, sans-serif;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  font-size: 0.75rem;
  color: var(--accent);
  margin: 0 0 0.6em;
}

h2 {
  font-size: 1.35rem;
  margin: 2.4em 0 0.6em;
  padding-top: 0.6em;
  border-top: 1px solid var(--rule);
}

h3 {
  font-size: 1.08rem;
  margin: 1.6em 0 0.5em;
}

p { margin: 0.9em 0; }

a { color: var(--accent); text-decoration-color: var(--rule); text-underline-offset: 3px; }
a:hover { text-decoration-color: var(--accent); }

ul, ol { padding-left: 1.3em; }
li { margin: 0.35em 0; }

strong { font-weight: 700; }

em.term { font-style: italic; color: var(--accent); }

code, pre, .mono {
  font-family: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  font-size: 0.85em;
}

code {
  background: var(--code-bg);
  padding: 0.1em 0.35em;
  border-radius: 3px;
}

pre {
  background: var(--code-bg);
  padding: 1em;
  border-radius: 6px;
  overflow-x: auto;
}
pre code { background: none; padding: 0; }

blockquote {
  margin: 1.2em 0;
  padding: 0.2em 1.2em;
  border-left: 3px solid var(--rule);
  color: var(--ink-soft);
  font-style: italic;
}

hr {
  border: none;
  border-top: 1px solid var(--rule);
  margin: 2.5em 0;
}

/* --- Nav / breadcrumbs --- */
.lesson-nav {
  font-family: -apple-system, "Helvetica Neue", Arial, sans-serif;
  font-size: 0.85rem;
  display: flex;
  justify-content: space-between;
  gap: 1em;
  color: var(--ink-soft);
  margin-bottom: 2.5em;
}
.lesson-nav a { color: var(--ink-soft); }

/* --- Callout boxes --- */
.box {
  border: 1px solid var(--rule);
  background: #fff;
  border-radius: 8px;
  padding: 1.1em 1.3em;
  margin: 1.4em 0;
}
.box.source {
  background: var(--accent-soft);
  border-color: var(--accent);
}
.box.win {
  border-left: 4px solid var(--accent);
}
.box .label {
  font-family: -apple-system, "Helvetica Neue", Arial, sans-serif;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-size: 0.72rem;
  color: var(--accent);
  margin-bottom: 0.5em;
  font-weight: 700;
}

/* --- Mechanism box: why / what-if / connects-to, forces transfer over recall --- */
.box.mech {
  border-left: 4px solid var(--good);
  background: #fff;
}
.box.mech .label { color: var(--good); }
.box.mech dl { margin: 0; }
.box.mech dt {
  font-family: -apple-system, "Helvetica Neue", Arial, sans-serif;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-size: 0.72rem;
  color: var(--good);
  font-weight: 700;
  margin: 1em 0 0.3em;
}
.box.mech dt:first-child { margin-top: 0; }
.box.mech dd { margin: 0 0 0.2em; }

/* --- Figures --- */
figure { margin: 1.5em 0; }
figure img, figure svg { width: 100%; height: auto; display: block; border-radius: 6px; border: 1px solid var(--rule); }
figcaption {
  font-family: -apple-system, "Helvetica Neue", Arial, sans-serif;
  font-size: 0.82rem;
  color: var(--ink-soft);
  margin-top: 0.5em;
  text-align: center;
}

/* --- Tables --- */
table { border-collapse: collapse; width: 100%; margin: 1.2em 0; font-size: 0.92em; }
th, td { text-align: left; padding: 0.45em 0.7em; border-bottom: 1px solid var(--rule); }
th { font-family: -apple-system, "Helvetica Neue", Arial, sans-serif; font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.05em; color: var(--ink-soft); }

/* --- Quiz component --- */
.quiz {
  border: 1px solid var(--rule);
  border-radius: 8px;
  padding: 1.2em 1.4em;
  margin: 1.4em 0;
  background: #fff;
}
.quiz .qhead {
  font-family: -apple-system, "Helvetica Neue", Arial, sans-serif;
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--ink-soft);
  margin-bottom: 0.6em;
  display: flex;
  justify-content: space-between;
}
.quiz .qtext { font-weight: 600; margin-bottom: 0.8em; }
.quiz .options { display: flex; flex-direction: column; gap: 0.5em; }
.quiz .opt {
  font-family: -apple-system, "Helvetica Neue", Arial, sans-serif;
  font-size: 0.95rem;
  text-align: left;
  border: 1px solid var(--rule);
  background: var(--bg);
  border-radius: 6px;
  padding: 0.6em 0.9em;
  cursor: pointer;
  color: var(--ink);
}
.quiz .opt:hover { border-color: var(--accent); }
.quiz .opt.correct { background: var(--good-bg); border-color: var(--good); }
.quiz .opt.wrong { background: var(--bad-bg); border-color: var(--bad); }
.quiz .opt:disabled { cursor: default; }
.quiz .feedback {
  font-family: -apple-system, "Helvetica Neue", Arial, sans-serif;
  font-size: 0.88rem;
  margin-top: 0.8em;
  padding-top: 0.7em;
  border-top: 1px dashed var(--rule);
  display: none;
}
.quiz .feedback.show { display: block; }
.quiz .feedback.good { color: var(--good); }
.quiz .feedback.bad { color: var(--bad); }

.quiz.free .answer-reveal {
  font-family: -apple-system, "Helvetica Neue", Arial, sans-serif;
  font-size: 0.88rem;
  margin-top: 0.8em;
}
.quiz.free .reveal-btn {
  font-family: -apple-system, "Helvetica Neue", Arial, sans-serif;
  font-size: 0.85rem;
  border: 1px solid var(--rule);
  background: var(--bg);
  border-radius: 6px;
  padding: 0.45em 0.9em;
  cursor: pointer;
  color: var(--ink-soft);
}
.quiz.free textarea {
  width: 100%;
  font-family: inherit;
  font-size: 0.95rem;
  border: 1px solid var(--rule);
  border-radius: 6px;
  padding: 0.6em;
  margin-bottom: 0.6em;
  resize: vertical;
  min-height: 3.2em;
}
.quiz.free .model-answer {
  display: none;
  background: var(--code-bg);
  border-radius: 6px;
  padding: 0.7em 0.9em;
  margin-top: 0.6em;
}
.quiz.free .model-answer.show { display: block; }

.quiz-score {
  font-family: -apple-system, "Helvetica Neue", Arial, sans-serif;
  font-size: 0.85rem;
  color: var(--ink-soft);
  text-align: right;
  margin-top: -0.5em;
}

/* --- Math (KaTeX) --- */
.katex { font-size: 1.05em; }
.katex-display { margin: 0.9em 0; overflow-x: auto; overflow-y: hidden; padding: 0.2em 0; }

/* --- Step-by-step worked calculation --- */
.calc {
  border: 1px solid var(--rule);
  border-radius: 8px;
  padding: 1em 1.3em 0.6em;
  margin: 1.6em 0;
  background: #fff;
}
.calc > .calc-title {
  font-family: -apple-system, "Helvetica Neue", Arial, sans-serif;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-size: 0.72rem;
  font-weight: 700;
  color: var(--accent);
  margin-bottom: 0.6em;
}
.calc .given {
  background: var(--accent-soft);
  border-radius: 6px;
  padding: 0.5em 1em;
  margin: 0.4em 0 0.8em;
  font-size: 0.95em;
}
ol.steps { list-style: none; counter-reset: st; padding: 0; margin: 0.6em 0; }
ol.steps > li {
  counter-increment: st;
  position: relative;
  padding: 0.1em 0 0.9em 2.6em;
  margin: 0;
}
ol.steps > li::before {
  content: counter(st);
  position: absolute;
  left: 0; top: 0.15em;
  width: 1.85em; height: 1.85em;
  border-radius: 50%;
  background: var(--accent);
  color: #fff;
  font-family: -apple-system, "Helvetica Neue", Arial, sans-serif;
  font-weight: 700;
  font-size: 0.8rem;
  text-align: center;
  line-height: 1.85em;
}
ol.steps > li > .st-title { font-weight: 700; margin-bottom: 0.15em; }
ol.steps > li p { margin: 0.3em 0; }
.answer {
  background: var(--good-bg);
  border-left: 4px solid var(--good);
  border-radius: 4px;
  padding: 0.5em 1em;
  margin: 0.6em 0 0.8em;
}
.answer .katex-display { margin: 0.4em 0; }
.plain-thai {
  font-size: 0.93em;
  color: var(--ink-soft);
  border-left: 3px solid var(--rule);
  padding-left: 0.9em;
  margin: 0.6em 0;
}
.plain-thai::before {
  content: "อ่านเป็นภาษาคน: ";
  font-weight: 700;
  color: var(--ink);
}
.box.beginner {
  border-left: 4px solid #2b5fa5;
  background: #fff;
}
.box.beginner .label { color: #2b5fa5; }
.eqtable td, .eqtable th { vertical-align: middle; }

/* Compact tables (calculation tables inside .calc / worked examples) */
table.compact { font-size: 0.85em; }
table.compact th, table.compact td { padding: 0.3em 0.55em; }

/* Verbatim instructor emphasis (slide text the lecturer coloured) */
mark.src { background: #fff1a8; color: inherit; padding: 0 0.12em; border-radius: 2px; }
.box.exam { border-left: 4px solid #c0392b; background: #fff; }
.box.exam .label { color: #c0392b; }
.box.exam ul { margin: 0.3em 0 0; }
.box.prereq { border-left: 4px solid #7a5cc7; background: #fff; }
.box.prereq .label { color: #7a5cc7; }
table.codeexp td:first-child { font-family: ui-monospace, "SF Mono", Menlo, Consolas, monospace; font-size: 0.85em; white-space: pre-wrap; }