/* ─────────────────────────────────────────────────────────────────────────────
   Course page — hero with the poster, section tabs, content with a sticky
   summary beside it, and other courses.
   ───────────────────────────────────────────────────────────────────────────── */

@layer page {

  /* ── Hero ───────────────────────────────────────────────────────────────── */
  .course-hero {
    position: relative;
    isolation: isolate;
    padding-top: calc(var(--header-h) + clamp(2.5rem, 1.5rem + 3vw, 4.5rem));
    padding-bottom: clamp(2.5rem, 1.5rem + 3vw, 4rem);
  }
  .course-hero .ambient { --glow-a: 24% 50%; --glow-b: 80% 40%; }
  .course-hero__grid {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.05fr);
    align-items: center;
    gap: clamp(2rem, 1rem + 4vw, 5rem);
  }
  .course-hero__copy { display: grid; gap: var(--s-4); }
  .course-hero__chips { display: flex; flex-wrap: wrap; gap: var(--s-2); }
  .course-hero__title { font-size: clamp(2.2rem, 1.5rem + 2.8vw, 3.6rem); line-height: var(--lh-tight); }
  .course-hero__lead { color: var(--ink-2); font-size: var(--fs-lead); line-height: 1.85; max-width: 34rem; }
  .course-hero__actions { display: flex; flex-wrap: wrap; gap: var(--s-3); margin-top: var(--s-2); }

  .course-hero__poster {
    padding: 10px;
    border-radius: var(--r-lg);
    background: rgb(255 255 255 / 0.82);
    border: 1px solid var(--white);
    box-shadow: var(--shadow-inset), var(--shadow-lg);
    rotate: -1.2deg;
  }
  .course-hero__poster img {
    width: 100%;
    aspect-ratio: 16 / 9;
    object-fit: cover;
    border-radius: calc(var(--r-lg) - 10px);
  }

  /* ── Section tabs (a scroll-spy marks the section in view) ──────────────── */
  .course-tabs {
    position: sticky;
    top: calc(var(--header-h) + var(--s-4));
    z-index: 5;
    margin-bottom: var(--s-8);
  }
  .course-tabs__list {
    display: flex;
    gap: var(--s-1);
    width: fit-content;
    max-width: 100%;
    padding: var(--s-2);
    overflow-x: auto;
    scrollbar-width: none;
    border-radius: var(--r-pill);
    background: rgb(255 255 255 / 0.72);
    border: 1px solid var(--glass-border);
    box-shadow: var(--shadow-inset), var(--shadow-md);
    backdrop-filter: var(--glass-blur);
    -webkit-backdrop-filter: var(--glass-blur);
  }
  .course-tabs__list::-webkit-scrollbar { display: none; }
  .course-tabs__link {
    display: block;
    padding: var(--s-2) var(--s-4);
    border-radius: var(--r-pill);
    color: var(--ink-2);
    font-size: var(--fs-small);
    font-weight: 500;
    white-space: nowrap;
    transition: background-color var(--dur-base) var(--ease-out), color var(--dur-fast) linear;
  }
  .course-tabs__link:hover { color: var(--ink); }
  .course-tabs__link[aria-current="true"] { background: var(--pink-soft); color: var(--pink-strong); }

  /* ── Body ───────────────────────────────────────────────────────────────── */
  .course-body {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(0, 22rem);
    align-items: start;
    gap: clamp(2rem, 1rem + 4vw, 4.5rem);
    padding-bottom: var(--section-y);
  }
  .course-body__main { display: grid; gap: var(--s-12); }
  .course-section { display: grid; gap: var(--s-5); scroll-margin-top: calc(var(--header-h) + 6rem); }
  .course-section__title { font-size: var(--fs-h3); display: flex; align-items: center; gap: var(--s-3); }
  .course-section__title::before {
    content: "";
    width: 0.35rem;
    height: 1.4em;
    border-radius: var(--r-pill);
    background: linear-gradient(180deg, var(--pink), var(--pink-border));
  }
  .course-section__text { color: var(--ink-2); line-height: 2; max-width: 44rem; }

  .course-outcomes { gap: var(--s-4); }
  .course-outcomes li { line-height: 1.9; }

  /* Syllabus: stages on a vertical line. */
  .syllabus { position: relative; display: grid; gap: var(--s-5); }
  .syllabus::before {
    content: "";
    position: absolute;
    top: 0.6rem;
    bottom: 0.6rem;
    inset-inline-start: 0.55rem;
    width: 2px;
    border-radius: 2px;
    background: linear-gradient(180deg, var(--pink), var(--pink-border));
  }
  .syllabus__stage { position: relative; display: flex; gap: var(--s-5); }
  .syllabus__node {
    position: relative;
    z-index: 1;
    flex: none;
    width: 1.1rem;
    height: 1.1rem;
    margin-top: 0.4rem;
    border-radius: 50%;
    background: var(--white);
    box-shadow: 0 0 0 3px var(--pink), 0 0 0 7px var(--pink-mist);
  }
  .syllabus__content {
    flex: 1;
    padding: var(--s-5) var(--s-6);
    border-radius: var(--r-md);
    background: var(--glass-solid);
    border: 1px solid var(--white);
    box-shadow: var(--shadow-inset), var(--shadow-sm);
  }
  .syllabus__title { font-size: 1.15rem; margin-bottom: var(--s-3); color: var(--pink-strong); }
  .syllabus__items { display: grid; gap: var(--s-2); color: var(--ink-2); }
  .syllabus__items li { position: relative; padding-inline-start: var(--s-5); line-height: 1.9; }
  .syllabus__items li::before {
    content: "";
    position: absolute;
    top: 0.85em;
    inset-inline-start: 0;
    width: 0.4rem;
    height: 0.4rem;
    border-radius: 50%;
    background: var(--pink-border);
  }

  .course-features { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: var(--s-3); }
  .course-feature {
    display: flex;
    align-items: flex-start;
    gap: var(--s-3);
    padding: var(--s-5);
    border-radius: var(--r-md);
    background: var(--glass-solid);
    border: 1px solid var(--white);
    box-shadow: var(--shadow-inset), var(--shadow-sm);
    line-height: 1.85;
  }
  .course-feature__icon {
    display: grid;
    place-items: center;
    flex: none;
    width: 2.4rem;
    height: 2.4rem;
    border-radius: var(--r-sm);
    background: var(--pink-soft);
    color: var(--pink-strong);
  }
  .course-feature__icon svg { width: 1.2rem; height: 1.2rem; }

  .course-fit { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .course-fit__card {
    display: grid;
    align-content: start;
    gap: var(--s-3);
    padding: var(--s-6);
    border-radius: var(--r-lg);
    background: linear-gradient(160deg, rgb(255 255 255 / 0.9), var(--pink-mist));
    border: 1px solid var(--white);
    box-shadow: var(--shadow-inset), var(--shadow-sm);
  }
  .course-fit__icon {
    display: grid;
    place-items: center;
    width: 2.75rem;
    height: 2.75rem;
    border-radius: 50%;
    background: var(--white);
    color: var(--pink);
    box-shadow: var(--shadow-sm);
  }
  .course-fit__icon svg { width: 1.3rem; height: 1.3rem; }
  .course-fit__title { font-size: 1.15rem; }
  .course-fit__card p { color: var(--ink-2); line-height: 1.9; }

  /* ── Summary aside ──────────────────────────────────────────────────────── */
  .course-body__aside { position: sticky; top: calc(var(--header-h) + 5.5rem); }
  .course-summary { display: grid; gap: var(--s-5); padding: var(--s-6); border-radius: var(--r-lg); }
  .course-summary__title { font-size: 1.2rem; }
  .course-summary__facts { display: grid; }
  .course-summary__row {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: var(--s-4);
    padding-block: var(--s-3);
    border-bottom: 1px solid var(--line);
    font-size: var(--fs-small);
  }
  .course-summary__row:last-child { border-bottom: 0; }
  .course-summary__row dt { display: inline-flex; align-items: center; gap: var(--s-2); color: var(--ink-2); white-space: nowrap; }
  .course-summary__row dt svg { width: 1.05rem; height: 1.05rem; color: var(--pink); }
  .course-summary__row dd { font-weight: 500; text-align: end; }
  .course-summary__note { display: block; margin-top: 2px; color: var(--ink-2); font-size: var(--fs-caption); font-weight: 400; }

  .course-summary__cta {
    display: grid;
    gap: var(--s-2);
    padding: var(--s-5);
    border-radius: var(--r-md);
    background: linear-gradient(150deg, var(--pink-soft), rgb(255 255 255 / 0.8));
    border: 1px solid var(--pink-border);
  }
  .course-summary__cta-title { font-family: var(--font-display); font-size: 1.2rem; font-weight: 700; }
  .course-summary__cta-text { color: var(--ink-2); font-size: var(--fs-small); line-height: 1.85; }
  .course-summary__btn { margin-top: var(--s-2); width: 100%; }
  .course-summary__back { justify-self: center; margin-top: var(--s-2); font-size: var(--fs-small); }

  .course-related .catalog__grid { margin-top: 0; }

  @media (max-width: 1080px) {
    .course-body { grid-template-columns: minmax(0, 1fr); }
    .course-body__aside { position: static; order: -1; }
  }
  @media (max-width: 900px) {
    .course-hero__grid { grid-template-columns: minmax(0, 1fr); }
    .course-hero__poster { order: -1; rotate: 0deg; }
  }
  @media (max-width: 640px) {
    .course-features, .course-fit { grid-template-columns: minmax(0, 1fr); }
    .course-hero__actions .btn { flex: 1 1 100%; }
    .syllabus__content { padding: var(--s-4); }
  }
}