/* Course documentation — design layer on top of Furo.
 *
 * The palette is not invented: every colour here is sampled from the course
 * hero image (docs/images/hero.png), so the site, the banner and the favicon
 * are the same identity. Link colours are contrast-checked against each
 * theme's background — #4f46e5 is 6.3:1 on white, #a5b4fc is 9.3:1 on the
 * Furo dark surface — so neither mode relies on the reader having good eyes.
 */

:root {
  --course-navy:   #0a1021;
  --course-blue:   #3cbaf8;
  --course-indigo: #818cf8;
  --course-pink:   #f273b8;
  --course-arc: linear-gradient(90deg, var(--course-blue), var(--course-indigo), var(--course-pink));
}

/* ── The course arc ──────────────────────────────────────────────────────
 * The hero cropped to its curve: the title is already the page's <h1>, so
 * repeating it in an image would just be the same words twice. What is left
 * is the part that carries information — the arc of the curriculum.
 */
.course-arc {
  margin: 1.5rem 0 1.75rem;
}
.course-arc img {
  display: block;
  width: 100%;
  border-radius: 12px;
  /* The banner is dark in both themes, so give it a hairline that reads on
     a white page without boxing it in on a dark one. */
  box-shadow: 0 0 0 1px rgb(129 140 248 / 22%);
}

/* ── Stat chips ─────────────────────────────────────────────────────────── */
.course-stats {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin: 0 0 1.75rem;
  padding: 0;
  list-style: none;
}
.course-stats li {
  margin: 0;
  padding: 0.3rem 0.75rem;
  border: 1px solid var(--color-background-border);
  border-radius: 999px;
  font-size: 0.8125rem;
  line-height: 1.5;
  color: var(--color-foreground-muted);
  white-space: nowrap;
}
.course-stats li b {
  color: var(--color-brand-content);
  font-weight: 700;
}

/* ── "Where to start" → cards ────────────────────────────────────────────
 * Scoped by section id so it styles this list and nothing else. The list
 * stays ordinary Markdown, so Sphinx still resolves and link-checks every
 * href — a hand-written <a href="…html"> would not survive a page move.
 */
#where-to-start > ul {
  display: grid;
  gap: 0.85rem;
  grid-template-columns: repeat(auto-fit, minmax(13.5rem, 1fr));
  margin: 1.25rem 0 0;
  padding: 0;
  list-style: none;
}
#where-to-start > ul > li {
  margin: 0;
  padding: 1rem 1.1rem;
  border: 1px solid var(--color-background-border);
  border-radius: 12px;
  background: var(--color-background-secondary);
  font-size: 0.925rem;
  line-height: 1.55;
  transition: border-color 0.15s ease, transform 0.15s ease;
}
#where-to-start > ul > li:hover {
  border-color: var(--color-brand-primary);
  transform: translateY(-2px);
}
#where-to-start > ul > li > strong:first-child {
  display: block;
  margin-bottom: 0.3rem;
  color: var(--color-brand-content);
}

/* ── "Browse the course" → a module grid ─────────────────────────────────
 * The toctree still generates this list, so adding a module needs no edit
 * here. Only the landing page's grid is restyled; the mini-book chapter
 * toctrees stay a numbered list, because those have a reading order and a
 * grid would throw it away.
 */
#browse-the-course .toctree-wrapper > p.caption {
  margin: 1.75rem 0 0.6rem;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-foreground-muted);
}
#browse-the-course .toctree-wrapper > ul {
  display: grid;
  gap: 0.6rem;
  grid-template-columns: repeat(auto-fill, minmax(14.5rem, 1fr));
  margin: 0;
  padding: 0;
  list-style: none;
}
#browse-the-course .toctree-wrapper > ul > li {
  margin: 0;
}
#browse-the-course .toctree-wrapper > ul > li > a {
  display: block;
  padding: 0.6rem 0.8rem;
  border: 1px solid var(--color-background-border);
  border-left: 3px solid var(--color-brand-primary);
  border-radius: 8px;
  font-size: 0.9rem;
  font-weight: 600;
  text-decoration: none;
  transition: background 0.15s ease, border-color 0.15s ease;
}
#browse-the-course .toctree-wrapper > ul > li > a:hover {
  background: var(--color-background-secondary);
  border-color: var(--color-brand-primary);
}
/* A module page's own chapter list would otherwise nest inside the card. */
#browse-the-course .toctree-wrapper > ul > li > ul {
  display: none;
}

/* ── Reading comfort ─────────────────────────────────────────────────────
 * Furo's default measure runs wide on a large monitor; long prose is easier
 * to track at a shorter line length. Tables and code keep the full width.
 */
article[role="main"] > section > p,
article[role="main"] > section > section > p,
article[role="main"] > section > ul,
article[role="main"] > section > section > ul {
  max-width: 46rem;
}

/* A hairline in the brand gradient under the page title, so the identity is
 * present on every page without needing a banner on every page. */
article[role="main"] > section > h1 {
  padding-bottom: 0.5rem;
  border-bottom: 2px solid transparent;
  border-image: var(--course-arc) 1;
}

@media (max-width: 46em) {
  .course-stats li { font-size: 0.75rem; }
  .course-arc { margin: 1.25rem 0; }
}