/* Course reader stylesheet — course-builder skill.
   PALETTE: re-derive per subject by editing ONLY the :root block plus the three
   literals marked "palette literal" below. Role guide:
     --board   dark chalkboard color (header band, code blocks)
     --chalk   light text on the board
     --paper   page background          --ink / --ink-soft  body text
     --manila / --manila-edge           reading-packet folder
     --stamp   accent: links, § marks, labels, exercise edge
   Default palette (chalkboard green / manila) shown; keep the contrast
   relationships when you change hues. */

:root {
  --board: #1e3a31;
  --board-2: #162c25;
  --chalk: #f2efe6;
  --paper: #fbf9f4;
  --ink: #23281f;
  --ink-soft: #5a6053;
  --manila: #ecdfb9;
  --manila-edge: #d3c294;
  --stamp: #9c3b2a;
  --ok: #3d6b4f;
  --card-line: #e3ddcc;     /* hairlines on paper */
  --field: #fffdf8;         /* inputs */
  --field-edge: #d8d2c0;
  --serif: 'EB Garamond', Georgia, serif;
  --sans: 'Public Sans', system-ui, sans-serif;
  --mono: 'IBM Plex Mono', ui-monospace, monospace;
}

* { box-sizing: border-box; margin: 0; }

body {
  background: var(--paper);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 1.12rem;
  line-height: 1.65;
}

a { color: var(--stamp); }
a:focus-visible, button:focus-visible { outline: 2px solid var(--board); outline-offset: 2px; }

/* ---------- chalkboard band ---------- */
.board {
  background:
    radial-gradient(ellipse at 20% 10%, rgba(242,239,230,0.06), transparent 55%),
    var(--board);
  color: var(--chalk);
  padding: 2.5rem 1.5rem 2.25rem;
  border-bottom: 6px solid var(--board-2);
}
.board-inner { max-width: 60rem; margin: 0 auto; }
.eyebrow {
  font-family: var(--sans);
  font-size: 0.72rem; font-weight: 600;
  letter-spacing: 0.28em; text-transform: uppercase;
  color: #b8c9b6;                    /* palette literal: muted chalk, tint of --board */
}
.board h1 {
  font-weight: 500;
  font-size: clamp(1.9rem, 5vw, 3rem);
  line-height: 1.15;
  margin: 0.5rem 0 0.75rem;
}
.board .dek { max-width: 56ch; font-size: 1.15rem; color: #d9dfd2; } /* palette literal */
.board a { color: var(--chalk); }

.chalk-rule {
  width: 7rem; height: 3px; margin-top: 1.25rem;
  background: linear-gradient(90deg, var(--chalk) 60%, transparent);
  opacity: 0.7; border-radius: 2px;
}

/* ---------- layout ---------- */
main { max-width: 60rem; margin: 0 auto; padding: 2.5rem 1.5rem 4rem; }
.lecture { max-width: 44rem; }
.lecture h2 { font-weight: 600; font-size: 1.55rem; margin: 2.25rem 0 0.75rem; }
.lecture h2::before { content: '§ '; color: var(--stamp); }
.lecture p { margin-bottom: 1rem; }
.lecture ul, .lecture ol { margin: 0 0 1rem 1.4rem; }
.lecture li { margin-bottom: 0.5rem; }
.lecture strong { font-weight: 600; }

.cite { font-style: italic; }
.smallcaps { font-variant: small-caps; letter-spacing: 0.04em; }

/* ---------- code as chalkboard ---------- */
pre {
  background: var(--board); color: var(--chalk);
  font-family: var(--mono); font-size: 0.78rem; line-height: 1.55;
  padding: 1.1rem 1.25rem; border-radius: 4px;
  overflow-x: auto; margin: 0 0 1rem;
  border-left: 4px solid var(--manila-edge);
}
code { font-family: var(--mono); font-size: 0.85em; }
p code, li code { background: #efe9da; padding: 0.05em 0.35em; border-radius: 3px; } /* palette literal */

/* ---------- manila reading packet ---------- */
.packet {
  background: var(--manila);
  border: 1px solid var(--manila-edge);
  border-top: 14px solid var(--manila-edge);
  border-radius: 6px 14px 6px 6px;
  padding: 1.25rem 1.4rem;
  margin: 2rem 0;
  box-shadow: 2px 3px 0 rgba(35,40,31,0.12);
}
.packet-label {
  font-family: var(--sans); font-size: 0.7rem; font-weight: 700;
  letter-spacing: 0.24em; text-transform: uppercase;
  color: var(--stamp); margin-bottom: 0.6rem;
}
.packet ul { list-style: none; margin: 0; }
.packet li {
  font-size: 0.98rem; margin-bottom: 0.65rem;
  padding-left: 1.1rem; text-indent: -1.1rem;
}
.packet li::before { content: '▤ '; color: var(--stamp); }

/* ---------- seminar question ---------- */
.seminar {
  border-left: 4px solid var(--board);
  padding: 0.4rem 0 0.4rem 1.1rem;
  margin: 2rem 0;
  font-size: 1.05rem;
}
.seminar .packet-label { color: var(--board); }

/* ---------- exercises: worksheet cards ---------- */
.exercise {
  background: #fff;
  border: 1px solid var(--card-line);
  border-left: 4px solid var(--stamp);
  border-radius: 4px;
  padding: 1.15rem 1.35rem 1.25rem;
  margin: 1.9rem 0;
  font-size: 1rem;
  box-shadow: 2px 3px 0 rgba(35,40,31,0.07);
}
.ex-label {
  font-family: var(--sans); font-size: 0.7rem; font-weight: 700;
  letter-spacing: 0.24em; text-transform: uppercase;
  color: var(--stamp); margin-bottom: 0.55rem;
}
.exercise .ex-prompt { margin-bottom: 0.7rem; }
.ex-meta {
  font-family: var(--sans); font-size: 0.75rem;
  color: var(--ink-soft); margin-top: 0.4rem;
}

/* quiz options */
.exercise label {
  display: block; padding: 0.45rem 0.65rem; margin-bottom: 0.15rem;
  border: 1px solid transparent; border-radius: 3px; cursor: pointer;
}
.exercise label:hover { background: var(--paper); }
.exercise label.is-right { background: #e8efe3; border-color: #9db38f; }
.exercise label.is-wrong { background: #f4e3de; border-color: #c98d7d; }
.exercise input[type="radio"] { accent-color: var(--board); margin-right: 0.35rem; }

/* buttons */
.exercise button {
  font-family: var(--sans); font-size: 0.74rem; font-weight: 700;
  letter-spacing: 0.14em; text-transform: uppercase;
  background: var(--board); color: var(--chalk);
  border: 0; border-radius: 3px; padding: 0.55rem 1.1rem;
  cursor: pointer; margin-top: 0.7rem;
}
.exercise button:hover { background: var(--board-2); }

/* result line */
.exercise .result {
  font-family: var(--sans); font-size: 0.88rem;
  margin-top: 0.6rem; min-height: 1.2em;
}
.exercise .result.ok { color: var(--ok); }
.exercise .result.no { color: var(--stamp); }

/* text workspaces */
.exercise textarea {
  width: 100%; font: inherit; font-size: 1rem; line-height: 1.5;
  padding: 0.7rem 0.85rem; margin-top: 0.35rem;
  border: 1px solid var(--field-edge); border-radius: 3px;
  background: var(--field); color: var(--ink); resize: vertical;
}
.exercise.code textarea { font-family: var(--mono); font-size: 0.82rem; line-height: 1.55; }
.exercise textarea:focus-visible { outline: 2px solid var(--board); outline-offset: 1px; }

/* reveals */
.exercise details {
  margin-top: 1rem; border-top: 1px dashed var(--field-edge); padding-top: 0.75rem;
}
.exercise summary {
  font-family: var(--sans); font-size: 0.8rem; font-weight: 700;
  letter-spacing: 0.06em; color: var(--stamp); cursor: pointer;
}
.exercise details > *:not(summary) { margin-top: 0.7rem; }
.exercise details pre { font-size: 0.76rem; }

/* run output */
.exercise .output {
  background: var(--board); color: var(--chalk);
  font-family: var(--mono); font-size: 0.8rem; line-height: 1.55;
  padding: 0.8rem 1rem; border-radius: 3px; margin-top: 0.7rem;
  white-space: pre-wrap; overflow-x: auto;
}

/* project + teaching assistant */
.exercise.project { border-left-color: var(--board); }
.exercise .ta { margin-top: 0.8rem; }
.exercise .ta button { margin-right: 0.6rem; }
.exercise .ta .copy-grade {
  background: transparent; color: var(--board);
  border: 1px solid var(--board);
}
.exercise .ta .copy-grade:hover { background: var(--paper); }
.ta-reply {
  margin-top: 0.9rem; padding: 0.9rem 1rem;
  background: var(--paper); border: 1px solid var(--card-line);
  border-left: 4px solid var(--board); border-radius: 3px;
  font-size: 0.98rem; white-space: pre-wrap;
}
.ta-reply::before {
  content: 'From your TA';
  display: block;
  font-family: var(--sans); font-size: 0.68rem; font-weight: 700;
  letter-spacing: 0.24em; text-transform: uppercase;
  color: var(--board); margin-bottom: 0.5rem;
}
.ta-key-row { margin-top: 0.8rem; }
.ta-key-row input {
  font-family: var(--mono); font-size: 0.8rem;
  width: 100%; max-width: 26rem;
  padding: 0.5rem 0.65rem; margin-right: 0.5rem; margin-bottom: 0.4rem;
  border: 1px solid var(--field-edge); border-radius: 3px; background: var(--field);
}
.ta-key-row .ex-meta { margin-top: 0.2rem; }

/* diagram exercise */
.exercise.diagram svg, figure.diagram-fig svg { width: 100%; height: auto; display: block; }
.exercise .labels { margin: 0.8rem 0 0 1.4rem; }
.exercise .labels li { margin-bottom: 0.45rem; }
.exercise select {
  font: inherit; font-size: 0.95rem; padding: 0.25rem 0.45rem;
  border: 1px solid var(--field-edge); border-radius: 3px; background: var(--field);
}
.exercise select.is-right { border-color: #9db38f; background: #e8efe3; }
.exercise select.is-wrong { border-color: #c98d7d; background: #f4e3de; }

/* expository figures */
figure.diagram-fig { margin: 1.75rem 0; }
figure.diagram-fig figcaption {
  font-family: var(--sans); font-size: 0.8rem; color: var(--ink-soft);
  margin-top: 0.45rem;
}

/* ---------- syllabus (home) ---------- */
.syllabus { list-style: none; margin: 0; padding: 0; }
.syllabus li { margin-bottom: 0.9rem; }
.syllabus a {
  display: grid;
  grid-template-columns: 4.5rem 1fr;
  gap: 0 1.25rem;
  text-decoration: none; color: inherit;
  background: #fff;
  border: 1px solid var(--card-line);
  border-radius: 4px;
  padding: 1.1rem 1.3rem;
  transition: transform 120ms ease, border-color 120ms ease;
}
.syllabus a:hover { transform: translateX(4px); border-color: var(--board); }
.week-no {
  grid-row: span 2;
  font-family: var(--sans); font-weight: 700; font-size: 0.72rem;
  letter-spacing: 0.16em; text-transform: uppercase;
  color: var(--stamp);
  border-right: 1px solid var(--card-line);
  display: flex; align-items: center;
}
.week-title { font-size: 1.25rem; font-weight: 600; }
.week-blurb { color: var(--ink-soft); font-size: 0.98rem; }

.notice {
  font-family: var(--sans); font-size: 0.85rem; color: var(--ink-soft);
  border-top: 1px solid var(--card-line); margin-top: 2.5rem; padding-top: 1rem;
  max-width: 70ch;
}

/* ---------- prev/next ---------- */
.pager {
  display: flex; justify-content: space-between; gap: 1rem;
  font-family: var(--sans); font-size: 0.9rem;
  border-top: 1px solid var(--card-line); margin-top: 3rem; padding-top: 1.25rem;
}
.pager a { text-decoration: none; }
.pager a:hover { text-decoration: underline; }

.topnav {
  font-family: var(--sans); font-size: 0.78rem; letter-spacing: 0.1em;
  text-transform: uppercase; margin-bottom: 0.75rem;
}
.topnav a { color: #b8c9b6; text-decoration: none; }  /* palette literal: match .eyebrow */
.topnav a:hover { color: var(--chalk); }

@media (max-width: 600px) {
  .syllabus a { grid-template-columns: 1fr; }
  .week-no { border-right: none; grid-row: auto; margin-bottom: 0.3rem; }
}
@media (prefers-reduced-motion: reduce) {
  .syllabus a { transition: none; }
}