/* Style for the hand-written pages: the landing page, course lecture lists, reference pages.
   Colours and fonts come from tokens.css. */

*, *::before, *::after { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  padding: 5rem 16px 4rem;
  color: var(--ink);
  background-color: var(--bg);
  background-image:
    radial-gradient(55% 50% at 70% 30%, var(--glow-b), transparent 70%),
    radial-gradient(45% 45% at 15% 85%, var(--glow-a), transparent 70%);
  background-attachment: fixed;
  font: 400 16px/1.55 var(--f-ui);
  -webkit-font-smoothing: antialiased;
}
/* faint star field, dark mode only */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  opacity: var(--stars);
  background-image:
    radial-gradient(1px 1px at 8% 14%, #fff 50%, transparent 51%),
    radial-gradient(1px 1px at 23% 61%, #fff 50%, transparent 51%),
    radial-gradient(1.5px 1.5px at 37% 27%, #fff 50%, transparent 51%),
    radial-gradient(1px 1px at 51% 83%, #fff 50%, transparent 51%),
    radial-gradient(1px 1px at 64% 9%, #fff 50%, transparent 51%),
    radial-gradient(1.5px 1.5px at 72% 52%, #fff 50%, transparent 51%),
    radial-gradient(1px 1px at 84% 77%, #fff 50%, transparent 51%),
    radial-gradient(1px 1px at 93% 31%, #fff 50%, transparent 51%),
    radial-gradient(1px 1px at 3% 92%, #fff 50%, transparent 51%),
    radial-gradient(1.5px 1.5px at 43% 96%, #fff 50%, transparent 51%);
}

main {
  position: relative;
  max-width: 680px;
  margin: 0 auto;
  padding: 30px 34px 28px;
  background: var(--panel);
  border: 1px solid var(--edge);
  border-radius: 20px;
  -webkit-backdrop-filter: blur(14px);
  backdrop-filter: blur(14px);
}

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

.back {
  font: 400 12px var(--f-mono);
  letter-spacing: 0.04em;
  color: var(--ink-soft);
  text-decoration: none;
}
.back:hover { color: var(--accent); }

.kicker {
  margin: 22px 0 6px;
  font: 500 12px var(--f-mono);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
}
h1 {
  margin: 0 0 10px;
  font-size: 38px;
  line-height: 1.1;
  font-weight: 800;
  letter-spacing: -0.025em;
  text-wrap: balance;
}
.meta { margin: 0; color: var(--ink-soft); }
.meta strong { color: var(--ink); font-weight: 500; }
.about {
  margin: 16px 0 0;
  padding-top: 16px;
  border-top: 1px solid var(--line);
}
.about p { margin: 0 0 10px; font: 400 17px/1.625 var(--f-serif); }
.about p:last-child { margin-bottom: 0; }

h2 {
  margin: 32px 0 12px;
  font: 500 12px var(--f-mono);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-soft);
}

ul.cards { list-style: none; margin: 0; padding: 0; display: grid; gap: 10px; }

.card {
  position: relative;
  display: block;
  padding: 14px 18px;
  background: var(--card);
  border: 1px solid var(--edge);
  border-radius: 14px;
  color: inherit;
  text-decoration: none;
  transition: border-color 0.15s ease, background-color 0.15s ease;
}
.card:hover, .card:focus-within { border-color: var(--accent); }
a.card:hover { background: var(--accent-soft); }

.num {
  font: 500 11px var(--f-mono);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
}
.name {
  display: block;
  margin-top: 3px;
  font-size: 18px;
  line-height: 1.3;
  font-weight: 700;
  letter-spacing: -0.01em;
}
.desc { display: block; margin-top: 4px; font: 400 15px/1.5 var(--f-serif); color: var(--ink-soft); }

/* a lecture card has several targets: the whole card opens the slides, the chips sit above it */
.card .name a { color: inherit; text-decoration: none; }
.card .name a::after { content: ""; position: absolute; inset: 0; border-radius: inherit; }
.links { position: relative; z-index: 1; display: flex; flex-wrap: wrap; gap: 6px; margin-top: 10px; }
.links a {
  padding: 3px 10px;
  font: 500 12px var(--f-mono);
  border: 1px solid var(--edge);
  border-radius: 999px;
  text-decoration: none;
  color: var(--ink-soft);
  background: var(--bg);
}
.links a:hover { color: var(--accent); border-color: var(--accent); }

kbd {
  padding: 0 5px;
  font: 500 12px var(--f-mono);
  border: 1px solid var(--edge);
  border-radius: 4px;
}

footer {
  margin-top: 28px;
  padding-top: 14px;
  border-top: 1px solid var(--line);
  font-size: 13px;
  color: var(--ink-soft);
}

#themeToggle {
  position: fixed;
  left: 16px;
  bottom: 16px;
  z-index: 10;
  width: 36px;
  height: 36px;
  display: grid;
  place-items: center;
  padding: 0;
  color: var(--ink);
  background: var(--panel);
  border: 1px solid var(--edge);
  border-radius: 8px;
  cursor: pointer;
}
#themeToggle:hover { border-color: var(--accent); }
#themeToggle svg { width: 18px; height: 18px; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; }
:root[data-theme="light"] #themeToggle .sun, :root:not([data-theme="light"]) #themeToggle .moon { display: none; }

@media (max-width: 540px) {
  body { padding-top: 2rem; }
  main { padding: 22px 20px 20px; }
  h1 { font-size: 30px; }
}

/* Reference pages (e.g. notation): text and tables inside a .prose block */
main.wide { max-width: 820px; }
.prose p { margin: 0 0 12px; }
.table-wrap { overflow-x: auto; margin: 0 0 8px; }
.prose table {
  width: 100%;
  border-collapse: collapse;
  font-size: 15px;
}
.prose th, .prose td {
  padding: 8px 10px;
  text-align: left;
  vertical-align: top;
  border-bottom: 1px solid var(--line);
}
.prose th {
  font: 500 11px var(--f-mono);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-soft);
  border-bottom-color: var(--edge);
}
.prose td:first-child { white-space: nowrap; }
.prose tbody tr:hover { background: var(--accent-soft); }