/* Arduino Course — single stylesheet */

:root {
  --bg: #fffaf2;
  --surface: #ffffff;
  --ink: #1a1a1a;
  --ink-soft: #555;
  --accent: #c44d20;        /* warm Arduino-ish orange-red */
  --accent-soft: #fde2d4;
  --ok: #1f7a3a;
  --ok-soft: #d6f0df;
  --warn: #b85d00;
  --warn-soft: #ffe9c8;
  --danger: #b51c1c;
  --danger-soft: #fbd8d8;
  --border: #e6dccb;
  --code-bg: #1f2430;
  --code-ink: #f4f4f4;
  --radius: 12px;
  --pad: 1.25rem;
  --maxw: 720px;
  font-size: 18px;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Helvetica Neue", Arial, sans-serif;
  line-height: 1.6;
}

body.dyslexic {
  font-family: "OpenDyslexic", -apple-system, sans-serif;
}

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

/* Layout */
.shell {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 1rem var(--pad) 5rem;
}

.topbar {
  position: sticky;
  top: 0;
  background: var(--bg);
  border-bottom: 2px solid var(--border);
  z-index: 10;
  padding: 0.6rem var(--pad);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  font-size: 0.95rem;
}
.topbar .home-link {
  font-weight: 700;
  color: var(--ink);
  text-decoration: none;
}
.topbar .progress {
  flex: 1;
  height: 8px;
  background: var(--accent-soft);
  border-radius: 999px;
  overflow: hidden;
  max-width: 240px;
}
.topbar .progress > div {
  height: 100%;
  background: var(--accent);
  width: 0%;
  transition: width 0.3s;
}
.topbar .toggles button {
  background: none;
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 0.25rem 0.7rem;
  cursor: pointer;
  font-size: 0.85rem;
}

/* Headings */
h1 { font-size: 2rem; margin: 1rem 0 0.4rem; line-height: 1.2; }
h2 { font-size: 1.4rem; margin: 1.6rem 0 0.4rem; color: var(--accent); }
h3 { font-size: 1.15rem; margin: 1.2rem 0 0.3rem; }
p { margin: 0.6rem 0; }

/* Hero */
.hero {
  background: linear-gradient(135deg, var(--accent-soft), #fff);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}
.hero h1 { margin-top: 0; }
.hero .subtitle { color: var(--ink-soft); font-size: 1.05rem; }
.hero .cta {
  display: inline-block;
  margin-top: 0.8rem;
  background: var(--accent);
  color: #fff;
  padding: 0.7rem 1.2rem;
  border-radius: 999px;
  text-decoration: none;
  font-weight: 700;
}

/* Lesson grid */
.lesson-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.8rem;
}
.lesson-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 0.9rem 1rem;
  display: flex;
  align-items: center;
  gap: 0.9rem;
  text-decoration: none;
  color: var(--ink);
}
.lesson-card:hover { border-color: var(--accent); }
.lesson-card .num {
  background: var(--accent);
  color: #fff;
  width: 2.2rem;
  height: 2.2rem;
  border-radius: 50%;
  display: grid;
  place-items: center;
  font-weight: 700;
  flex-shrink: 0;
}
.lesson-card.locked .num { background: #bbb; }
.lesson-card.locked { opacity: 0.65; }
.lesson-card .meta {
  font-size: 0.85rem;
  color: var(--ink-soft);
  margin-top: 0.15rem;
}
.lesson-card .body { flex: 1; }
.lesson-card .arrow { color: var(--accent); font-size: 1.4rem; }

/* Block heading between lesson groups */
.block-heading {
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--ink-soft);
  margin: 1.5rem 0 0.4rem;
  padding-left: 0.2rem;
}

/* Sections inside a lesson */
.lesson-section {
  margin: 1.2rem 0;
}
.lesson-section img,
.lesson-section svg {
  max-width: 100%;
  height: auto;
  border-radius: var(--radius);
  border: 1px solid var(--border);
}
.lesson-section figcaption {
  font-size: 0.9rem;
  color: var(--ink-soft);
  text-align: center;
  margin-top: 0.4rem;
}

/* Callouts */
.callout {
  border-left: 5px solid var(--accent);
  background: var(--accent-soft);
  padding: 0.8rem 1rem;
  border-radius: 8px;
  margin: 1rem 0;
}
.callout.tip { border-color: var(--ok); background: var(--ok-soft); }
.callout.warning { border-color: var(--warn); background: var(--warn-soft); }
.callout.safety { border-color: var(--danger); background: var(--danger-soft); }
.callout .label {
  font-weight: 700;
  text-transform: uppercase;
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  margin-bottom: 0.2rem;
}
.callout.tip .label { color: var(--ok); }
.callout.warning .label { color: var(--warn); }
.callout.safety .label { color: var(--danger); }

/* Code block */
pre.code {
  background: var(--code-bg);
  color: var(--code-ink);
  padding: 1rem 1.1rem;
  border-radius: var(--radius);
  overflow-x: auto;
  font-size: 0.92rem;
  line-height: 1.5;
}
code.inline {
  background: var(--accent-soft);
  border-radius: 4px;
  padding: 0.05rem 0.3rem;
  font-size: 0.95em;
}

/* Wokwi embed wrapper */
.wokwi-wrap {
  position: relative;
  padding-top: 60%;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--border);
  background: #f1ece2;
}
.wokwi-wrap iframe {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border: 0;
}

/* You will need */
.youwillneed {
  background: var(--surface);
  border: 1px dashed var(--border);
  border-radius: var(--radius);
  padding: 0.8rem 1rem;
}
.youwillneed h3 { margin-top: 0; }
.youwillneed ul { margin: 0.3rem 0 0 1rem; padding: 0; }

/* Glossary box at end of lesson */
.glossary-box {
  background: #f7f1e3;
  border-radius: var(--radius);
  padding: 1rem 1.2rem;
  margin-top: 2rem;
}
.glossary-box dt { font-weight: 700; margin-top: 0.4rem; }
.glossary-box dd { margin: 0.1rem 0 0.4rem 0; color: var(--ink-soft); }

/* Quiz */
.quiz {
  border: 2px solid var(--accent);
  border-radius: var(--radius);
  padding: 1rem 1.2rem;
  margin-top: 2rem;
  background: var(--surface);
}
.quiz h2 { margin-top: 0; }
.quiz .q { margin: 1rem 0; }
.quiz .q .stem { font-weight: 600; }
.quiz .opts { list-style: none; padding: 0; margin: 0.4rem 0; }
.quiz .opts li {
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.55rem 0.8rem;
  margin: 0.3rem 0;
  cursor: pointer;
  background: #fff;
}
.quiz .opts li:hover { border-color: var(--accent); }
.quiz .opts li.correct { background: var(--ok-soft); border-color: var(--ok); }
.quiz .opts li.wrong { background: var(--danger-soft); border-color: var(--danger); }
.quiz .opts li.disabled { cursor: default; pointer-events: none; }
.quiz .explain {
  margin-top: 0.4rem;
  font-size: 0.92rem;
  color: var(--ink-soft);
  display: none;
}
.quiz .explain.show { display: block; }

/* Prev / Next nav */
.lesson-nav {
  display: flex;
  justify-content: space-between;
  gap: 0.8rem;
  margin: 2.5rem 0 0;
}
.lesson-nav a, .lesson-nav span {
  flex: 1;
  text-align: center;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 0.7rem 1rem;
  text-decoration: none;
  color: var(--ink);
  font-weight: 600;
}
.lesson-nav a:hover { border-color: var(--accent); }
.lesson-nav .disabled { opacity: 0.4; }
.lesson-nav .next { background: var(--accent); color: #fff; border-color: var(--accent); }

/* Footer */
footer {
  text-align: center;
  margin-top: 3rem;
  font-size: 0.85rem;
  color: var(--ink-soft);
}

/* ---- Visual section primitives ---- */

/* TL;DR card at top of lesson */
.tldr {
  background: linear-gradient(135deg, #fff4e6, #fff);
  border: 2px solid var(--accent);
  border-radius: var(--radius);
  padding: 1rem 1.2rem;
  margin: 1.2rem 0;
  display: flex;
  gap: 0.8rem;
  align-items: flex-start;
}
.tldr .tldr-icon {
  font-size: 1.6rem;
  line-height: 1;
  flex-shrink: 0;
}
.tldr .tldr-body { flex: 1; }
.tldr .tldr-label {
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  font-weight: 700;
  color: var(--accent);
  margin-bottom: 0.2rem;
}

/* Numbered step cards */
.steps {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.7rem;
  margin: 1rem 0;
}
.steps .step {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 0.9rem 1rem 0.9rem 3.4rem;
  position: relative;
}
.steps .step::before {
  content: attr(data-n);
  position: absolute;
  left: 0.9rem;
  top: 0.85rem;
  width: 1.9rem;
  height: 1.9rem;
  border-radius: 50%;
  background: var(--accent);
  color: #fff;
  font-weight: 700;
  display: grid;
  place-items: center;
  font-size: 0.95rem;
}
.steps .step .step-title {
  font-weight: 700;
  margin-bottom: 0.2rem;
}
.steps .step p { margin: 0.2rem 0; }

/* Card grid (2 or 3 columns) */
.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 0.8rem;
  margin: 1rem 0;
}
.cards .card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 0.9rem 1rem;
}
.cards .card .icon {
  font-size: 1.6rem;
  display: block;
  margin-bottom: 0.3rem;
}
.cards .card .card-title {
  font-weight: 700;
  margin-bottom: 0.2rem;
  color: var(--accent);
}

/* Side-by-side compare */
.compare {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.7rem;
  margin: 1rem 0;
}
.compare > div {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 0.9rem 1rem;
}
.compare h4 {
  margin: 0 0 0.4rem;
  color: var(--accent);
  font-size: 1rem;
}
@media (max-width: 480px) {
  .compare { grid-template-columns: 1fr; }
}

/* Chips / badges */
.chips {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin: 0.8rem 0;
}
.chips .chip {
  background: var(--accent-soft);
  color: var(--accent);
  font-weight: 600;
  font-size: 0.85rem;
  padding: 0.3rem 0.7rem;
  border-radius: 999px;
}

/* Inline SVG diagram wrapper */
.diagram-svg {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem;
  margin: 1rem 0;
  text-align: center;
}
.diagram-svg svg {
  max-width: 100%;
  height: auto;
  display: block;
  margin: 0 auto;
}
.diagram-svg .diagram-caption {
  font-size: 0.88rem;
  color: var(--ink-soft);
  margin-top: 0.5rem;
}

/* Big-number stats / facts row */
.facts {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(130px, 1fr));
  gap: 0.6rem;
  margin: 1rem 0;
}
.facts .fact {
  background: var(--accent-soft);
  border-radius: var(--radius);
  padding: 0.7rem;
  text-align: center;
}
.facts .fact .big {
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--accent);
  line-height: 1;
}
.facts .fact .small {
  font-size: 0.85rem;
  color: var(--ink-soft);
  margin-top: 0.2rem;
}

/* Mobile tweaks */
@media (max-width: 520px) {
  :root { font-size: 17px; }
  .topbar { flex-wrap: wrap; }
  .topbar .progress { order: 3; max-width: 100%; flex-basis: 100%; }
}