/* ============================================
   Design tokens
   ============================================ */
:root {
  --navy: #14213D;
  --paper: #F5F2EA;
  --track-a: #1F6F8B;   /* cyanotype blue */
  --track-b: #C77D2E;   /* ochre gold */
  --line: #6B7A8F;
  --ink: #1A1A1A;
  --paper-dim: #ECE7DA;

  --mono: 'IBM Plex Mono', 'JetBrains Mono', ui-monospace, Menlo, monospace;
  --serif: 'Source Serif 4', 'Lyon', Georgia, serif;
  --sans: 'IBM Plex Sans', 'Inter', -apple-system, sans-serif;

  --max-w: 780px;
  --wide-w: 980px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 18px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; }
a:focus-visible, button:focus-visible { outline: 2px solid var(--navy); outline-offset: 3px; }

img, svg { max-width: 100%; height: auto; display: block; }

/* ============================================
   Nav
   ============================================ */
.site-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: var(--wide-w);
  margin: 0 auto;
  padding: 28px 24px 20px;
  font-family: var(--sans);
}

.site-nav .brand {
  font-family: var(--mono);
  font-size: 15px;
  letter-spacing: 0.02em;
  text-decoration: none;
  color: var(--ink);
  font-weight: 600;
}

.nav-links {
  display: flex;
  gap: 28px;
  align-items: center;
  font-size: 14px;
}

.nav-links a { text-decoration: none; opacity: 0.75; }
.nav-links a:hover { opacity: 1; }

.switch-track {
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.03em;
  border: 1px solid var(--line);
  padding: 6px 12px;
  border-radius: 3px;
  text-decoration: none;
  opacity: 0.7;
}
.switch-track:hover { opacity: 1; border-color: var(--ink); }

/* ============================================
   Hero (home)
   ============================================ */
.hero {
  max-width: var(--wide-w);
  margin: 0 auto;
  padding: 60px 24px 40px;
}

.hero-thesis {
  font-family: var(--mono);
  font-weight: 500;
  font-size: clamp(24px, 4vw, 40px);
  line-height: 1.3;
  letter-spacing: -0.01em;
  max-width: 820px;
  margin: 0 0 12px;
}

.hero-mechanism {
  font-family: var(--mono);
  font-weight: 500;
  font-size: clamp(24px, 4vw, 40px);
  line-height: 1.3;
  letter-spacing: -0.01em;
  max-width: 820px;
  color: var(--ink);
  margin: 0 0 12px;
}

.hero-sub {
  font-family: var(--sans);
  font-size: 16px;
  color: #444;
  max-width: 600px;
  margin: 0 0 48px;
}

.rule {
  border: none;
  border-top: 1px solid var(--line);
  opacity: 0.4;
  margin: 40px 0;
}

/* ============================================
   Doors (track selection)
   ============================================ */
.doors {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}

@media (max-width: 720px) {
  .doors { grid-template-columns: 1fr; }
}

.door {
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 32px;
  text-decoration: none;
  color: var(--ink);
  display: block;
  transition: border-color 0.15s ease, transform 0.15s ease;
  position: relative;
  background: #fff;
}

.door:hover { transform: translateY(-2px); }

.door.track-a { border-top: 4px solid var(--track-a); }
.door.track-b { border-top: 4px solid var(--track-b); }

.door-label {
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--line);
  margin-bottom: 12px;
}

.door h2 {
  font-family: var(--sans);
  font-size: 22px;
  margin: 0 0 12px;
}

.door p {
  font-family: var(--sans);
  font-size: 15px;
  color: #444;
  margin: 0 0 18px;
}

.case-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.case-tag {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.03em;
  padding: 5px 10px;
  border-radius: 3px;
  border: 1px solid var(--line);
  color: var(--ink);
  opacity: 0.85;
}

.door.track-a .case-tag { border-color: var(--track-a); }
.door.track-b .case-tag { border-color: var(--track-b); }

/* ============================================
   Track landing pages
   ============================================ */
.track-header {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 48px 24px 32px;
}

.track-eyebrow {
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 16px;
}

.track-a-accent { color: var(--track-a); }
.track-b-accent { color: var(--track-b); }

.spine {
  font-family: var(--serif);
  font-size: 20px;
  line-height: 1.55;
  max-width: 700px;
}

.resume-link {
  display: inline-block;
  margin-top: 24px;
  font-family: var(--mono);
  font-size: 13px;
  border: 1px solid var(--ink);
  padding: 10px 16px;
  border-radius: 3px;
  text-decoration: none;
}
.resume-link:hover { background: var(--ink); color: var(--paper); }

.case-list {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px 80px;
}

.case-card {
  display: block;
  text-decoration: none;
  color: var(--ink);
  border-bottom: 1px solid var(--line);
  padding: 28px 0;
}
.case-card:first-child { border-top: 1px solid var(--line); }

.case-card-label {
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--line);
  margin-bottom: 8px;
}

.case-list.track-a-list .case-card-label { color: var(--track-a); }
.case-list.track-b-list .case-card-label { color: var(--track-b); }

.case-card h3 {
  font-family: var(--sans);
  font-size: 20px;
  margin: 0 0 6px;
}

.case-card p {
  font-family: var(--sans);
  font-size: 14px;
  color: #555;
  margin: 0;
}

/* ============================================
   Case study page
   ============================================ */
.cs-header {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 48px 24px 0;
}

.cs-accent-bar {
  height: 4px;
  width: 60px;
  margin-bottom: 20px;
}

.cs-title {
  font-family: var(--sans);
  font-size: clamp(24px, 4vw, 34px);
  line-height: 1.25;
  margin: 0 0 16px;
}

.cs-meta {
  font-family: var(--mono);
  font-size: 13px;
  color: var(--line);
  margin-bottom: 40px;
}

.cs-meta span { margin-right: 18px; }

.cs-body {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px 80px;
}

.cs-section {
  display: grid;
  grid-template-columns: 160px 1fr;
  gap: 24px;
  padding: 32px 0;
  border-top: 1px solid var(--line);
  position: relative;
}

.cs-section:first-child { border-top: none; }

.cs-label {
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--line);
  padding-top: 3px;
}

.cs-text p { margin: 0 0 16px; }
.cs-text p:last-child { margin-bottom: 0; }

.cs-diagram {
  margin: 8px 0 40px;
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 20px;
  background: #fff;
}

.cs-crosslink {
  font-family: var(--sans);
  font-size: 14px;
  padding-top: 32px;
  border-top: 1px solid var(--line);
  margin-top: 8px;
}

.cs-crosslink a { text-decoration: underline; }

.parked-note {
  font-family: var(--sans);
  font-size: 15px;
  color: #555;
  border: 1px dashed var(--line);
  border-radius: 4px;
  padding: 24px;
  margin: 24px 0 60px;
}

/* ============================================
   About / Notes
   ============================================ */
.page-body {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 48px 24px 80px;
}

.page-body h1 {
  font-family: var(--sans);
  font-size: 30px;
  margin-bottom: 24px;
}

.page-body p { margin: 0 0 18px; }

footer {
  max-width: var(--wide-w);
  margin: 0 auto;
  padding: 40px 24px 60px;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--line);
}

.li-icon {
  display: inline-flex;
  align-items: center;
  color: var(--line);
  opacity: 0.8;
  transition: opacity 0.15s ease, color 0.15s ease;
}
.li-icon:hover { opacity: 1; color: var(--ink); }
.li-icon svg { width: 18px; height: 18px; }