/* IAR Masterclass — field notebook / robotics lab */
:root {
  --ink: #12110e;
  --ink-2: #1b1a16;
  --ink-3: #24221c;
  --paper: #e8dfc8;
  --paper-2: #d4c9ad;
  --paper-dim: #a89b7e;
  --amber: #e8a54b;
  --amber-hot: #f3c36a;
  --amber-dim: #8a6230;
  --rule: #2e2b24;
  --rule-2: #3d392f;
  --ok: #8faf74;
  --danger: #c46b4a;
  --cyan-mute: #7a9aa0;
  --shadow: 0 18px 50px rgba(0,0,0,.45);
  --serif: "Source Serif 4", "Iowan Old Style", Palatino, Georgia, serif;
  --display: "Fraunces", "Source Serif 4", Georgia, serif;
  --sans: "IBM Plex Sans", "Helvetica Neue", sans-serif;
  --mono: "IBM Plex Mono", "IBM Plex Sans", ui-monospace, monospace;
  --max: 1120px;
  --rail: 248px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
html, body { margin: 0; padding: 0; }
body {
  background:
    radial-gradient(1200px 700px at 10% -10%, #2a2418 0%, transparent 55%),
    radial-gradient(900px 500px at 110% 10%, #1d221c 0%, transparent 50%),
    var(--ink);
  color: var(--paper);
  font-family: var(--sans);
  font-size: 16.5px;
  line-height: 1.55;
  min-height: 100vh;
}

a { color: var(--amber); text-decoration-color: rgba(232,165,75,.35); text-underline-offset: 3px; }
a:hover { color: var(--amber-hot); }
img { max-width: 100%; }

.skip {
  position: absolute; left: -999px; top: 0;
}
.skip:focus { left: 12px; top: 12px; background: var(--ink-2); padding: 8px 12px; z-index: 20; }

.mast {
  position: sticky; top: 0; z-index: 8;
  display: flex; align-items: center; gap: 28px;
  padding: 14px 28px;
  background: rgba(18,17,14,.86);
  border-bottom: 1px solid var(--rule);
  backdrop-filter: blur(10px);
}
.brand {
  display: flex; align-items: baseline; gap: 10px;
  color: inherit; text-decoration: none;
  min-width: 210px;
}
.brand-mark {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: .18em;
  text-transform: uppercase;
  color: var(--amber);
}
.brand-name {
  font-family: var(--display);
  font-weight: 600;
  font-size: 18px;
  letter-spacing: .01em;
}
.nav {
  display: flex; gap: 18px; flex: 1; flex-wrap: wrap;
}
.nav a {
  color: var(--paper-2);
  text-decoration: none;
  font-size: 13.5px;
  letter-spacing: .04em;
  text-transform: uppercase;
  font-family: var(--mono);
}
.nav a:hover, .nav a.is-on { color: var(--amber); }
.mast-meta {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--paper-dim);
  letter-spacing: .08em;
  text-transform: uppercase;
}

.wrap { width: min(var(--max), calc(100% - 48px)); margin: 0 auto; }
.page { padding: 42px 0 80px; }

.kicker {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: var(--amber);
  margin: 0 0 10px;
}
h1, h2, h3, h4 { font-family: var(--display); font-weight: 600; letter-spacing: -.01em; }
h1 { font-size: clamp(36px, 5vw, 64px); line-height: 1.05; margin: 0 0 16px; }
h2 { font-size: 28px; margin: 36px 0 12px; }
h3 { font-size: 20px; margin: 26px 0 8px; }
.lede {
  font-family: var(--serif);
  font-size: 21px;
  line-height: 1.45;
  color: var(--paper-2);
  max-width: 42rem;
}

.hero {
  display: grid;
  grid-template-columns: 1.2fr .8fr;
  gap: 48px;
  align-items: end;
  padding: 28px 0 12px;
}
.stamp {
  border: 1px dashed var(--amber-dim);
  padding: 18px 20px;
  background: linear-gradient(180deg, rgba(232,165,75,.06), transparent);
}
.stamp p { margin: 0 0 10px; color: var(--paper-2); font-size: 14px; }
.cite {
  font-family: var(--serif);
  font-style: italic;
  color: var(--paper);
  font-size: 14.5px;
}

.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 16px; }
.card {
  background: var(--ink-2);
  border: 1px solid var(--rule);
  padding: 20px 22px;
  box-shadow: var(--shadow);
  position: relative;
}
.card:hover { border-color: var(--amber-dim); }
.card h3 { margin-top: 0; }
.card p { color: var(--paper-2); margin: 0 0 12px; }
.card .num {
  font-family: var(--mono);
  color: var(--amber);
  font-size: 12px;
  letter-spacing: .14em;
}
.card a.cover { color: inherit; text-decoration: none; display: block; }
.tag {
  display: inline-block;
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: .12em;
  text-transform: uppercase;
  border: 1px solid var(--rule-2);
  padding: 3px 7px;
  color: var(--paper-dim);
  margin-right: 6px;
}

.map {
  display: grid;
  grid-template-columns: 140px 1fr;
  gap: 10px 18px;
  margin: 18px 0 8px;
}
.map h3 { margin: 6px 0 0; font-size: 13px; font-family: var(--mono); letter-spacing: .12em; text-transform: uppercase; color: var(--paper-dim); }
.chips { display: flex; flex-wrap: wrap; gap: 8px; }
.chip {
  display: inline-flex; align-items: center; gap: 8px;
  background: var(--ink-3);
  border: 1px solid var(--rule);
  padding: 8px 10px;
  color: var(--paper);
  text-decoration: none;
  font-size: 14px;
}
.chip:hover { border-color: var(--amber); color: var(--amber-hot); }
.chip small { color: var(--paper-dim); font-family: var(--mono); font-size: 10px; }

.lesson-layout {
  display: grid;
  grid-template-columns: var(--rail) 1fr;
  gap: 36px;
}
.rail {
  position: sticky; top: 76px; align-self: start;
  font-size: 13px;
}
.rail a { color: var(--paper-2); text-decoration: none; display: block; padding: 4px 0; }
.rail a:hover, .rail a.is-on { color: var(--amber); }
.rail .part { margin: 16px 0 6px; font-family: var(--mono); font-size: 10px; letter-spacing: .16em; text-transform: uppercase; color: var(--paper-dim); }
.done-dot { width: 7px; height: 7px; border-radius: 50%; background: var(--rule-2); display: inline-block; margin-right: 7px; }
.done-dot.on { background: var(--ok); box-shadow: 0 0 8px var(--ok); }

.note {
  font-family: var(--serif);
  font-size: 18px;
  line-height: 1.65;
  max-width: 42rem;
  color: #efe7d3;
}
.note p { margin: 0 0 1em; }
.note em { color: var(--paper); }

.goals { list-style: none; padding: 0; margin: 0 0 18px; }
.goals li {
  padding: 8px 0 8px 22px;
  border-bottom: 1px solid var(--rule);
  position: relative;
  color: var(--paper-2);
}
.goals li::before {
  content: "▹";
  position: absolute; left: 0; color: var(--amber);
}

.eq {
  background: #16140f;
  border-left: 3px solid var(--amber);
  padding: 16px 18px;
  margin: 18px 0;
  overflow-x: auto;
}
.eq .cap {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--paper-dim);
  margin-bottom: 8px;
}

.checks details {
  background: var(--ink-2);
  border: 1px solid var(--rule);
  padding: 12px 16px;
  margin: 10px 0;
}
.checks summary { cursor: pointer; font-weight: 500; }
.checks .ans { margin-top: 10px; color: var(--paper-2); font-family: var(--serif); }

.cta {
  display: flex; flex-wrap: wrap; gap: 12px; align-items: center;
  margin: 28px 0;
  padding: 18px;
  border: 1px solid var(--amber-dim);
  background: linear-gradient(90deg, rgba(232,165,75,.08), transparent);
}
.btn {
  display: inline-block;
  background: var(--amber);
  color: #1a1408;
  text-decoration: none;
  padding: 10px 14px;
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: .08em;
  text-transform: uppercase;
  font-weight: 500;
}
.btn:hover { background: var(--amber-hot); color: #1a1408; }
.btn.ghost {
  background: transparent;
  color: var(--paper);
  border: 1px solid var(--rule-2);
}
.pager { display: flex; justify-content: space-between; gap: 12px; margin-top: 36px; }
.pager a { text-decoration: none; color: var(--paper-2); }
.pager a:hover { color: var(--amber); }

.progress-row {
  display: flex; align-items: center; justify-content: space-between;
  gap: 12px; padding: 10px 0; border-bottom: 1px solid var(--rule);
}
mark-done {
  display: inline-flex; align-items: center; gap: 8px;
  font-family: var(--mono); font-size: 12px; color: var(--paper-dim);
}
mark-done button, .chk-btn {
  background: var(--ink-3);
  color: var(--paper);
  border: 1px solid var(--rule-2);
  padding: 7px 10px;
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: .08em;
  text-transform: uppercase;
  cursor: pointer;
}
.chk-btn.on { border-color: var(--ok); color: var(--ok); }

.studio-panel {
  background: #0e0d0b;
  border: 1px solid var(--rule);
  padding: 14px;
  margin: 16px 0 28px;
}
.studio-panel canvas {
  width: 100%;
  height: auto;
  display: block;
  background: #0a0908;
  border: 1px solid var(--rule);
  cursor: crosshair;
}
.controls {
  display: flex; flex-wrap: wrap; gap: 10px 16px; align-items: center;
  margin-top: 10px;
  font-family: var(--mono); font-size: 12px; color: var(--paper-dim);
}
.controls button {
  background: var(--ink-3); color: var(--paper); border: 1px solid var(--rule-2);
  padding: 6px 10px; font-family: var(--mono); cursor: pointer;
}
.controls button:hover { border-color: var(--amber); color: var(--amber); }
.controls input[type=range] { accent-color: var(--amber); width: 140px; }

.week {
  display: grid; grid-template-columns: 88px 1fr; gap: 8px 16px;
  padding: 10px 0; border-bottom: 1px solid var(--rule);
}
.week .w { font-family: var(--mono); color: var(--amber); font-size: 12px; letter-spacing: .1em; }
.foot {
  border-top: 1px solid var(--rule);
  padding: 28px 0 48px;
  color: var(--paper-dim);
  font-size: 13.5px;
}
.foot-grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr; gap: 24px; }
.foot a { color: var(--paper-2); }
.foot h4 { margin: 0 0 8px; font-size: 13px; font-family: var(--mono); letter-spacing: .12em; text-transform: uppercase; color: var(--amber); }

.rule { height: 1px; background: var(--rule); margin: 32px 0; }
.small { font-size: 13.5px; color: var(--paper-dim); }

@media (max-width: 880px) {
  .hero, .lesson-layout, .map, .grid-3, .grid-2, .foot-grid { grid-template-columns: 1fr; }
  .rail { position: static; }
  .mast { flex-wrap: wrap; gap: 10px; }
  .wrap { width: min(100% - 28px, var(--max)); }
  h1 { font-size: 36px; }
}