:root {
  --paper: #f2f5f7;
  --card: #ffffff;
  --ink: #182a3a;
  --muted: #52657a;
  --green: #0e7c52;
  --green-dark: #095c3d;
  --green-soft: #e3f1ea;
  --saffron: #c77c11;
  --saffron-text: #925806;
  --saffron-soft: #f8eedd;
  --blue-soft: #e7eef6;
  --rule: #d9e2ea;
  --code: #0e1b26;
  --code-ink: #d9e6f2;
  --danger: #9b3a32;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: "IBM Plex Sans", system-ui, sans-serif;
  font-size: 17px;
  line-height: 1.65;
}
a { color: var(--green); }
a:focus-visible, button:focus-visible {
  outline: 3px solid var(--saffron);
  outline-offset: 3px;
}
code, pre, .eyebrow, .step-chip, .wordmark, .lesson-tag, .tag,
.card-topline, .progress-status, .codecard-head, .checkpoint span,
.reflection > span {
  font-family: "IBM Plex Mono", monospace;
}

.wrap { max-width: 920px; margin: 0 auto; padding-left: 22px; padding-right: 22px; }
.topbar { background: rgba(255,255,255,.96); border-bottom: 1px solid var(--rule); }
.topbar-inner {
  max-width: 920px;
  margin: 0 auto;
  min-height: 58px;
  padding: 12px 22px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}
.wordmark { color: var(--ink); text-decoration: none; font-size: 13px; font-weight: 600; letter-spacing: .13em; }
.wordmark span { color: var(--green); }
.lesson-tag { color: var(--muted); font-size: 12px; letter-spacing: .08em; text-align: right; }

.hero { padding-top: 62px; padding-bottom: 42px; }
.hero-home { padding-top: 74px; padding-bottom: 34px; }
.eyebrow { margin: 0 0 9px; color: var(--saffron-text); font-size: 12.5px; font-weight: 600; letter-spacing: .14em; text-transform: uppercase; }
h1, h2, h3 { color: var(--ink); }
h1, .display-title { font-family: "IBM Plex Serif", Georgia, serif; }
h1 { max-width: 850px; margin: 0 0 20px; font-size: clamp(38px, 7vw, 62px); line-height: 1.08; letter-spacing: -.02em; }
h2 { margin: 0 0 12px; font-family: "IBM Plex Serif", Georgia, serif; font-size: clamp(25px, 4vw, 34px); line-height: 1.2; }
h3 { margin: 0 0 8px; font-size: 19px; line-height: 1.35; }
p { margin: 0 0 15px; }
.lede { max-width: 68ch; color: var(--muted); font-size: 19px; }
.lede strong { color: var(--ink); }
.meta-chips { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 22px; }
.chip, .tag {
  display: inline-flex;
  align-items: center;
  border: 1px solid var(--rule);
  border-radius: 999px;
  background: var(--card);
  color: var(--muted);
  font-size: 12px;
  padding: 5px 11px;
}

.scope-banner, .start-banner, .completion-card {
  border: 1px solid var(--green);
  border-radius: 16px;
  background: var(--green-soft);
  padding: 24px;
}
.start-banner { display: grid; grid-template-columns: 1fr auto; align-items: center; gap: 22px; margin-bottom: 38px; }
.start-banner h2, .completion-card h2 { font-size: 26px; }
.button, .complete-button {
  display: inline-flex;
  justify-content: center;
  align-items: center;
  min-height: 44px;
  border: 1px solid var(--green);
  border-radius: 9px;
  background: var(--green);
  color: white;
  cursor: pointer;
  font: 600 15px "IBM Plex Sans", sans-serif;
  padding: 10px 17px;
  text-decoration: none;
}
.button:hover, .complete-button:hover { background: var(--green-dark); }
.button.secondary { background: transparent; color: var(--green); }

.section-label { margin: 44px 0 15px; color: var(--muted); font: 600 13px "IBM Plex Mono", monospace; letter-spacing: .12em; text-transform: uppercase; }
.path-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 15px; }
.lesson-card {
  min-height: 245px;
  border: 1px solid var(--rule);
  border-radius: 15px;
  background: var(--card);
  color: var(--ink);
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding: 23px;
  text-decoration: none;
  transition: transform .15s ease, box-shadow .15s ease;
}
.lesson-card:hover { transform: translateY(-2px); box-shadow: 0 8px 22px rgba(24,42,58,.08); }
.lesson-card h3 { font-family: "IBM Plex Serif", Georgia, serif; font-size: 25px; }
.lesson-card p { color: var(--muted); font-size: 15.5px; }
.card-topline { display: flex; justify-content: space-between; gap: 12px; color: var(--saffron-text); font-size: 11.5px; font-weight: 600; letter-spacing: .06em; }
.progress-status { color: var(--muted); text-align: right; }
.progress-status.done { color: var(--green); }
.lesson-meta { display: flex; flex-wrap: wrap; gap: 7px; margin-top: auto; }
.tag.live { border-color: var(--green); background: var(--green-soft); color: var(--green); font-weight: 600; }
.lesson-card.soon { border-style: dashed; background: transparent; pointer-events: none; }

.course-rules, .decision-grid, .idea-grid { display: grid; gap: 14px; }
.course-rules { grid-template-columns: repeat(3, minmax(0, 1fr)); margin: 42px 0 64px; }
.rule-card, .decision-card, .idea-card {
  border: 1px solid var(--rule);
  border-radius: 13px;
  background: var(--card);
  padding: 20px;
}
.rule-card strong { display: block; margin-bottom: 7px; color: var(--green); }
.rule-card p, .decision-card p, .idea-card p { margin: 0; color: var(--muted); font-size: 15px; }
.decision-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); margin: 20px 0; }
.decision-card.selected { border-color: var(--green); background: var(--green-soft); }
.idea-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); margin: 20px 0; }

.step { margin: 0 0 28px; border: 1px solid var(--rule); border-radius: 16px; background: var(--card); padding: 27px; }
.step-chip { display: inline-block; margin-bottom: 12px; color: var(--saffron-text); font-size: 12px; font-weight: 600; letter-spacing: .1em; }
.step ul, .step ol { padding-left: 24px; }
.step li { margin-bottom: 7px; }
.step code:not(pre code) { border-radius: 5px; background: var(--blue-soft); padding: 1px 5px; font-size: .88em; }

.codecard { overflow: hidden; margin-top: 20px; border: 1px solid #24394a; border-radius: 11px; background: var(--code); }
.codecard-head { min-height: 44px; border-bottom: 1px solid #294153; display: flex; align-items: center; justify-content: space-between; gap: 16px; color: #9eb0bf; font-size: 11.5px; letter-spacing: .08em; padding: 8px 13px 8px 17px; }
.copy { border: 1px solid #506779; border-radius: 6px; background: transparent; color: #d9e6f2; cursor: pointer; font: 500 12px "IBM Plex Mono", monospace; padding: 6px 10px; }
.copy.done { border-color: #63c39e; color: #7ce0ba; }
pre { margin: 0; overflow-x: auto; color: var(--code-ink); font-size: 13.5px; line-height: 1.62; padding: 19px; tab-size: 4; }

.checkpoint { margin: 12px 0 0; border-left: 4px solid var(--green); background: var(--green-soft); padding: 13px 16px; }
.checkpoint span { color: var(--green); font-size: 11px; font-weight: 600; letter-spacing: .1em; }
.checkpoint p { margin: 4px 0 0; font-size: 14.5px; }
.callout { margin: 20px 0; border-left: 4px solid var(--saffron); background: var(--saffron-soft); padding: 18px 20px; }
.callout.green { border-color: var(--green); background: var(--green-soft); }
.callout.danger { border-color: var(--danger); background: #faecea; }
.callout p:last-child { margin-bottom: 0; }
.reflection { margin: 22px 0 0; border: 1px dashed var(--saffron); border-radius: 10px; background: #fffaf1; padding: 18px 20px; }
.reflection > span { color: var(--saffron-text); font-size: 11.5px; font-weight: 600; letter-spacing: .1em; }
.reflection ol { margin-bottom: 0; }

.tablewrap { overflow-x: auto; margin: 18px 0; }
table { width: 100%; border-collapse: collapse; background: var(--card); font-size: 15px; }
th, td { border: 1px solid var(--rule); padding: 12px 14px; text-align: left; vertical-align: top; }
th { background: var(--blue-soft); font-weight: 600; }
details { margin: 14px 0; border: 1px solid var(--rule); border-radius: 10px; background: var(--card); padding: 14px 17px; }
summary { cursor: pointer; font-weight: 600; }
details > *:not(summary) { margin-top: 12px; }

.completion-card { display: grid; grid-template-columns: 1fr auto; align-items: center; gap: 24px; margin: 46px 0 22px; }
.complete-button.is-done { background: var(--card); color: var(--green); }
.lesson-nav { display: flex; justify-content: space-between; gap: 18px; margin: 22px 0 64px; }
.lesson-nav a { font-weight: 600; text-decoration: none; }
footer { border-top: 1px solid var(--rule); background: var(--card); color: var(--muted); font-size: 14px; padding: 25px 0 42px; }
.foot-inner { max-width: 920px; margin: 0 auto; padding: 0 22px; display: flex; justify-content: space-between; gap: 20px; }

@media (max-width: 720px) {
  body { font-size: 16px; }
  .hero { padding-top: 44px; }
  .path-grid, .course-rules, .decision-grid, .idea-grid { grid-template-columns: 1fr; }
  .start-banner, .completion-card { grid-template-columns: 1fr; }
  .lesson-card { min-height: 0; }
  .step { padding: 21px 18px; }
  .lesson-tag { max-width: 45%; }
  .foot-inner { flex-direction: column; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { transition: none !important; }
}

/* Readability helpers for the beginner-friendly walkthrough */
.plain {
  margin: 16px 0;
  border-left: 4px solid var(--green);
  background: var(--green-soft);
  border-radius: 0 10px 10px 0;
  padding: 14px 18px;
}
.plain > span {
  display: block;
  color: var(--green-dark);
  font-size: 11.5px;
  font-weight: 600;
  letter-spacing: .1em;
  text-transform: uppercase;
  margin-bottom: 4px;
}
.plain p:last-child { margin-bottom: 0; }
.does {
  margin: 16px 0 8px;
  font-size: 15px;
  color: var(--muted);
}
.does strong { color: var(--ink); }
details.deep {
  margin: 16px 0;
  border: 1px solid var(--rule);
  border-radius: 10px;
  background: var(--card);
  padding: 10px 16px;
}
details.deep > summary {
  cursor: pointer;
  font-weight: 600;
  color: var(--saffron-text);
  font-size: 14.5px;
}
details.deep[open] > summary { margin-bottom: 8px; }
.term {
  font-style: normal;
  border-bottom: 1px dotted var(--saffron);
  cursor: help;
}