:root {
  --ink: #14181d;
  --ink-soft: #2a3038;
  --muted: #6b7480;
  --rule: #e3e6ea;
  --bg: #fdfcf9;
  --bg-soft: #f6f4ef;
  --paper: #fff;
  --accent: #1a3a5c;
  --accent-hover: #2d5685;
  --course-accent: #861f41;
  --danger: #9a2e2e;
  --focus: #2d71b8;
  --serif: "Source Serif 4", "Source Serif Pro", Newsreader, Georgia, "Times New Roman", serif;
  --mono: "JetBrains Mono", "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
  --content-width: 1180px;
  color-scheme: light;
}

*, *::before, *::after { box-sizing: border-box; }
[hidden] { display: none !important; }

html {
  background: var(--bg);
  color: var(--ink);
  scroll-behavior: smooth;
}

body {
  min-width: 300px;
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 19px;
  font-feature-settings: "kern" 1, "liga" 1;
  line-height: 1.62;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

button, input, select, textarea { font: inherit; }
button, select, summary, label, input[type="file"] { cursor: pointer; }
button:disabled, select:disabled { cursor: not-allowed; opacity: .48; }

a { color: var(--accent); text-underline-offset: .18em; }
a:hover { color: var(--accent-hover); }

:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--focus), transparent 20%);
  outline-offset: 3px;
}

h1, h2, h3, h4 {
  margin: 0;
  color: var(--ink);
  font-family: var(--serif);
  letter-spacing: -.012em;
  line-height: 1.13;
}

h1 { font-size: clamp(2.6rem, 8vw, 6.25rem); font-weight: 400; }
h2 { font-size: clamp(2rem, 4vw, 3.3rem); font-weight: 450; }
h3 { font-size: 1.45rem; font-weight: 550; }

p { color: var(--ink-soft); }
strong { color: var(--ink); font-weight: 600; }

kbd {
  display: inline-block;
  min-width: 1.7em;
  padding: .08em .35em;
  border: 1px solid #c9ced5;
  border-bottom-width: 2px;
  border-radius: 3px;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--mono);
  font-size: .78em;
  line-height: 1.45;
  text-align: center;
}

.sr-only {
  position: absolute !important;
  width: 1px !important;
  height: 1px !important;
  padding: 0 !important;
  margin: -1px !important;
  overflow: hidden !important;
  clip: rect(0, 0, 0, 0) !important;
  white-space: nowrap !important;
  border: 0 !important;
}

.skip-link {
  position: fixed;
  z-index: 10000;
  top: .65rem;
  left: .65rem;
  padding: .7rem 1rem;
  transform: translateY(-160%);
  border-radius: 2px;
  background: var(--accent);
  color: white;
  font-family: var(--mono);
  font-size: .88rem;
  text-decoration: none;
}
.skip-link:focus { transform: translateY(0); }

.eyebrow,
.tag,
.tool-kicker,
.build-note {
  margin: 0;
  color: var(--muted);
  font-family: var(--mono);
  font-size: .8rem;
  font-weight: 500;
  letter-spacing: .08em;
  line-height: 1.4;
  text-transform: uppercase;
}

.muted { color: var(--muted); }

.masthead {
  position: relative;
  z-index: 20;
  border-bottom: 1px solid var(--rule);
  background: color-mix(in srgb, var(--bg), transparent 2%);
}

.masthead-inner {
  display: flex;
  min-height: 78px;
  max-width: var(--content-width);
  align-items: center;
  justify-content: space-between;
  gap: 2rem;
  margin: 0 auto;
  padding: 1rem;
}

.site-name {
  color: var(--ink);
  font-size: 1.12rem;
  font-weight: 500;
  letter-spacing: -.005em;
  text-decoration: none;
}

.site-nav { display: flex; align-items: center; gap: clamp(1rem, 3vw, 2.25rem); }
.site-nav a {
  border-bottom: 1.5px solid transparent;
  color: var(--ink);
  font-family: var(--mono);
  font-size: .84rem;
  letter-spacing: .03em;
  text-decoration: none;
  text-transform: lowercase;
}
.site-nav a:hover,
.site-nav a[aria-current="page"] { border-bottom-color: var(--accent); color: var(--accent); }

.nav-toggle {
  display: none;
  min-width: 48px;
  min-height: 48px;
  border: 1px solid var(--rule);
  border-radius: 2px;
  background: transparent;
  color: var(--ink);
  font-family: var(--mono);
  font-size: .82rem;
  text-transform: lowercase;
}

.button,
button.button {
  display: inline-flex;
  min-height: 50px;
  align-items: center;
  justify-content: center;
  gap: .5em;
  padding: .78rem 1.1rem;
  border: 1px solid var(--accent);
  border-radius: 2px;
  background: var(--accent);
  color: white;
  font-family: var(--mono);
  font-size: .84rem;
  font-weight: 500;
  letter-spacing: .02em;
  line-height: 1.2;
  text-decoration: none;
}
.button:hover { border-color: var(--accent-hover); background: var(--accent-hover); color: white; }
.button-secondary { background: transparent; color: var(--accent); }
.button-secondary:hover { color: white; }

.text-action {
  display: inline-block;
  border-bottom: 1.5px solid transparent;
  color: var(--accent);
  font-family: var(--mono);
  font-size: .85rem;
  font-weight: 500;
  line-height: 1.5;
  text-decoration: none;
}
.text-action:hover { border-bottom-color: var(--accent-hover); }

.site-footer {
  margin-top: 4rem;
  border-top: 1px solid var(--rule);
  color: var(--muted);
}
.site-footer > div {
  display: grid;
  max-width: var(--content-width);
  grid-template-columns: 1fr auto auto;
  align-items: center;
  gap: 2rem;
  margin: 0 auto;
  padding: 1.5rem 1rem 2.5rem;
}
.site-footer p { margin: 0; color: var(--muted); font-size: .96rem; }
.site-footer nav { display: flex; gap: 1.25rem; }
.site-footer a { font-family: var(--mono); font-size: .78rem; text-decoration: none; }

@media (max-width: 720px) {
  body { font-size: 18px; }
  .nav-toggle { display: block; }
  .site-nav:not(.always-visible) {
    position: absolute;
    top: calc(100% + 1px);
    right: 0;
    left: 0;
    display: none;
    align-items: stretch;
    flex-direction: column;
    gap: 0;
    padding: .5rem 1rem 1rem;
    border-bottom: 1px solid var(--rule);
    background: var(--bg);
  }
  .site-nav.is-open { display: flex; }
  .site-nav:not(.always-visible) a { min-height: 44px; padding: .75rem .25rem; }
  .site-nav.always-visible { gap: 1rem; }
  .site-nav.always-visible a:not(:first-child) { display: none; }
  .site-footer > div { grid-template-columns: 1fr; gap: .75rem; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: .01ms !important; animation-iteration-count: 1 !important; transition-duration: .01ms !important; }
}