/* COMS 6113 course site — single page.
   Layout modeled on the Columbia DAP Lab "agentic-systems" course site. */

:root {
  --font: "Montserrat", "Helvetica Neue", Arial, sans-serif;
  --text: #142430;
  --muted: #536877;
  --bg: #f8fdff;
  --accent: #1d4f91;
  --accent-dark: #12345f;
  --tint: rgba(29, 79, 145, 0.05);
  --rule: rgba(20, 36, 48, 0.14);
  --header-h: 3.4rem;
}

html {
  font-size: 15px;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h) + 1.25rem);
}

body {
  box-sizing: border-box;
  max-width: 1600px;
  margin: 0 auto;
  padding: calc(var(--header-h) + 1rem) clamp(1rem, 4vw, 4rem) 0;
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  font-weight: 500;
  -webkit-font-smoothing: antialiased;
}

/* ---------- Header / nav ---------- */

.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(248, 253, 255, 0.95);
  backdrop-filter: blur(6px);
  border-bottom: 1px solid var(--rule);
}

.site-nav {
  box-sizing: border-box;
  max-width: 1600px;
  margin: 0 auto;
  padding: 0.95rem clamp(1rem, 4vw, 4rem) 0.85rem;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.55rem 1.75rem;
}

.site-nav a {
  font-size: 0.85rem;
  font-weight: 600;
  line-height: 1.2;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text);
  text-decoration: none;
  white-space: nowrap;
  padding: 0.25rem 0;
}

.site-nav a:hover,
.site-nav a:focus-visible {
  color: var(--accent);
}

.site-nav .course-code {
  font-weight: 800;
  color: var(--accent);
  margin-right: auto;
}

a:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

/* ---------- Main column ---------- */

article {
  min-width: 0;
}

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

h1 {
  font-size: clamp(1.9rem, 3vw, 2.8rem);
  font-weight: 800;
  letter-spacing: -0.015em;
  margin: 0.75rem 0 0.5rem;
  text-wrap: balance;
}

.subtitle {
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent);
  margin: 0 0 1.75rem;
}

h2 {
  font-size: clamp(1.5rem, 2vw, 1.9rem);
  font-weight: 700;
  letter-spacing: -0.01em;
  margin: 3rem 0 0;
  padding-bottom: 0.4rem;
  border-bottom: 2px solid var(--accent);
  max-width: 54rem;
}

h3 {
  font-size: clamp(1.1rem, 1.3vw, 1.25rem);
  font-weight: 700;
  color: var(--accent-dark);
  margin: 2rem 0 0;
}

article p,
article ul,
article ol {
  font-size: clamp(1.05rem, 0.95rem + 0.2vw, 1.15rem);
  line-height: 1.75;
  max-width: 54rem;
}

article ul,
article ol {
  padding-left: 1.4rem;
}

article li {
  padding-block: 0.15rem;
}

article li::marker {
  color: var(--accent);
}

article a {
  color: var(--accent);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 0.18em;
}

article a:hover {
  color: var(--accent-dark);
  text-decoration-thickness: 2px;
}

.tbd {
  color: var(--muted);
  font-style: italic;
}

.notice {
  box-sizing: border-box;
  margin: 1.25rem 0;
  padding: 0.85rem 1.1rem;
  border-left: 4px solid var(--accent);
  background: var(--tint);
  font-size: 1rem;
  line-height: 1.6;
}

/* ---------- Tables ---------- */

.table-wrapper {
  width: 100%;
  overflow-x: auto;
  margin: 1.4rem 0 2rem;
}

.table-wrapper:focus-visible {
  outline: 2px solid var(--muted);
  outline-offset: 4px;
}

table {
  width: 100%;
  border-collapse: collapse;
  border-top: 2px solid var(--text);
  border-bottom: 2px solid var(--text);
}

thead {
  border-bottom: 1px solid var(--text);
}

th,
td {
  padding: 0.85rem 0.8rem;
  text-align: left;
  vertical-align: top;
  font-size: 0.98rem;
  line-height: 1.55;
}

th {
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

tbody tr + tr {
  border-top: 1px solid var(--rule);
}

tbody tr:nth-child(even) {
  background: var(--tint);
}

.schedule table {
  min-width: 44rem;
  table-layout: fixed;
}

.schedule th:nth-child(1) { width: 4.5rem; }
.schedule th:nth-child(2) { width: 6.5rem; }
.schedule th:nth-child(4) { width: 30%; }

.schedule tr.break td {
  color: var(--muted);
  font-style: italic;
}

.topic {
  font-weight: 700;
}

.grading table {
  max-width: 36rem;
}

.grading td:nth-child(2),
.grading th:nth-child(2) {
  width: 8rem;
  text-align: right;
}

/* ---------- Right rail ---------- */

.course-rail {
  font-size: 0.95rem;
  line-height: 1.45;
}

.course-rail h2 {
  font-size: 0.85rem;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin: 0 0 0.35rem;
  padding: 0;
  border: 0;
}

.course-rail h3 {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--accent);
  margin: 0.9rem 0 0.15rem;
}

.course-rail ul {
  list-style: none;
  margin: 0 0 0 0.6rem;
  padding: 0;
}

.course-rail li {
  padding: 0.12rem 0 0.25rem;
}

.course-rail .detail {
  display: block;
}

.course-rail a {
  color: var(--accent);
  font-weight: 700;
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 0.15em;
}

.course-rail a:hover {
  color: var(--accent-dark);
  text-decoration-thickness: 2px;
}

.course-rail .role {
  color: var(--accent-dark);
  font-weight: 700;
}

.course-rail .staff-name {
  text-decoration: none;
}

.course-rail .staff-name:hover {
  text-decoration: underline;
}

/* ---------- Footer ---------- */

footer {
  margin-top: 4rem;
  padding: 1.25rem 0 2.5rem;
  border-top: 1px solid var(--rule);
  font-size: 0.85rem;
  line-height: 1.6;
  color: var(--muted);
}

footer a {
  color: inherit;
}

/* ---------- Responsive layout ---------- */

.course-shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  grid-template-areas:
    "title"
    "rail"
    "body";
}

.title-block { grid-area: title; }
.course-rail { grid-area: rail; }
.course-shell article { grid-area: body; }

@media screen and (min-width: 1120px) {
  .course-shell {
    grid-template-columns: minmax(0, 1fr) 18rem;
    grid-template-rows: auto 1fr;
    grid-template-areas:
      "title rail"
      "body  rail";
    column-gap: 2.5rem;
  }

  .course-rail {
    align-self: start;
    position: sticky;
    top: calc(var(--header-h) + 1.5rem);
    max-height: calc(100vh - var(--header-h) - 3rem);
    overflow-y: auto;
    margin-top: 0.75rem;
    padding: 0.9rem 0.75rem 0.9rem 1.25rem;
    border-left: 1px solid var(--rule);
  }
}

@media screen and (max-width: 1119px) {
  .course-rail {
    margin: 0 0 1rem;
    padding: 0.85rem 0;
    border-top: 1px solid var(--rule);
    border-bottom: 1px solid var(--rule);
  }
}

@media screen and (min-width: 761px) and (max-width: 1119px) {
  .course-rail {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 0.25rem 2rem;
  }

  .course-rail h2 {
    grid-column: 1 / -1;
  }

  .course-rail .rail-group h3:first-child {
    margin-top: 0;
  }
}

@media screen and (max-width: 760px) {
  :root {
    --header-h: 5rem;
  }

  .site-nav {
    gap: 0.2rem 0.9rem;
    padding: 0.55rem 0.85rem 0.5rem;
  }

  .site-nav .course-code {
    flex-basis: 100%;
  }

  .site-nav a {
    font-size: 0.75rem;
    letter-spacing: 0.08em;
  }
}

@media print {
  .site-header { display: none; }
  body { padding-top: 0; background: #fff; }
  .course-rail { position: static; border: 0; padding: 0; }
}