:root {
  --bg: #f7f5f0;
  --surface: #ffffff;
  --surface-2: #efece4;
  --text: #22201c;
  --muted: #6d675c;
  --line: #ddd7ca;
  --accent: #b4532a;
  --accent-soft: #f6e3d8;
  --root: #b4532a;
  --tone: #2f5d73;
  --target: #c8891c;
  --dim: #b9b3a6;
  --ok: #2e7d4f;
  --ok-soft: #e1f1e6;
  --bad: #b23a3a;
  --bad-soft: #f7e0e0;
  --wood: #efe2cc;
  --fret: #a59d8d;
  --string: #7f786b;
  --radius: 10px;
  --font: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --mono: ui-monospace, "SFMono-Regular", Menlo, monospace;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #181714;
    --surface: #211f1b;
    --surface-2: #2a2823;
    --text: #ece7dc;
    --muted: #a39c8e;
    --line: #3a372f;
    --accent: #e0814f;
    --accent-soft: #3b2a20;
    --root: #e0814f;
    --tone: #6aa6c2;
    --target: #e6b34a;
    --dim: #5b574e;
    --ok: #6cc08e;
    --ok-soft: #1f3327;
    --bad: #e07777;
    --bad-soft: #3a2222;
    --wood: #2c2821;
    --fret: #6f6858;
    --string: #8d8676;
    color-scheme: dark;
  }
}

* { box-sizing: border-box; }
html { scroll-padding-top: 70px; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.6 var(--font);
  -webkit-font-smoothing: antialiased;
}
a { color: var(--accent); }
.muted { color: var(--muted); }
.small { font-size: 0.88rem; }

/* ---------- top bar ---------- */
.topbar {
  position: sticky; top: 0; z-index: 20;
  display: flex; align-items: center; gap: 12px;
  height: 56px; padding: 0 16px;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}
.brand { display: inline-flex; align-items: center; gap: 8px; font-weight: 700; color: var(--text); text-decoration: none; letter-spacing: -0.01em; }
.brand img { display: block; }
.metro { margin-left: auto; display: flex; align-items: center; gap: 6px; }
.metro input {
  width: 64px; padding: 4px 6px; font: inherit; font-size: 0.9rem;
  background: var(--surface); color: var(--text); border: 1px solid var(--line); border-radius: 6px;
}
.menu-btn { display: none; }

/* ---------- layout ---------- */
.layout { display: grid; grid-template-columns: 290px minmax(0, 1fr); }
.sidebar {
  position: sticky; top: 56px; height: calc(100vh - 56px); overflow-y: auto;
  padding: 16px 12px 40px; border-right: 1px solid var(--line);
}
main { min-width: 0; }
.page { max-width: 820px; margin: 0 auto; padding: 32px 24px 80px; }

.nav-home { display: block; padding: 6px 10px; border-radius: 6px; color: var(--text); text-decoration: none; font-weight: 600; }
.nav-home.active, .nav-item.active { background: var(--accent-soft); }
.nav-progress { padding: 8px 10px 4px; font-size: 0.82rem; }
.bar { height: 6px; background: var(--surface-2); border-radius: 3px; overflow: hidden; margin-bottom: 4px; }
.bar span { display: block; height: 100%; background: var(--ok); }
.nav-phase { margin: 18px 10px 6px; font-size: 0.72rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em; color: var(--muted); }
.nav-item {
  display: flex; align-items: center; gap: 10px; padding: 5px 10px; border-radius: 6px;
  color: var(--text); text-decoration: none; font-size: 0.93rem; line-height: 1.3;
}
.nav-item:hover { background: var(--surface-2); }
.nav-num {
  flex: none; width: 24px; height: 24px; border-radius: 50%; display: grid; place-items: center;
  font-size: 0.75rem; font-weight: 600; background: var(--surface-2); color: var(--muted);
}
.nav-item.done .nav-num { background: var(--ok); color: #fff; }
.nav-item.done .nav-title { color: var(--muted); }
.nav-sub { margin-left: auto; font-size: 0.75rem; color: var(--muted); }

/* ---------- type ---------- */
h1 { font-size: 2.1rem; line-height: 1.15; letter-spacing: -0.02em; margin: 0.2em 0 0.4em; }
h2 { font-size: 1.4rem; letter-spacing: -0.01em; margin: 1.6em 0 0.4em; }
h3 { font-size: 1.08rem; margin: 0; }
.eyebrow { margin: 0; font-size: 0.8rem; font-weight: 600; text-transform: uppercase; letter-spacing: 0.08em; color: var(--accent); }
.lede { font-size: 1.12rem; color: var(--muted); margin: 0 0 1.2em; }
.prose p { margin: 0.6em 0; }
.prose ul, .prose ol { padding-left: 1.3em; }
.prose li { margin: 0.25em 0; }
.prose code, code { font-family: var(--mono); font-size: 0.9em; background: var(--surface-2); padding: 1px 5px; border-radius: 4px; }
.prose table { border-collapse: collapse; width: 100%; margin: 0.8em 0; font-size: 0.93rem; display: block; overflow-x: auto; }
.prose th, .prose td { border: 1px solid var(--line); padding: 6px 10px; text-align: left; white-space: nowrap; }
.prose th { background: var(--surface-2); font-weight: 600; }
.prose blockquote { margin: 0.8em 0; padding: 0.2em 1em; border-left: 3px solid var(--line); color: var(--muted); }
.prose kbd { font-family: var(--mono); font-size: 0.85em; border: 1px solid var(--line); border-radius: 4px; padding: 0 4px; }

.block { margin: 1.4em 0; }
.prereq { font-size: 0.92rem; margin-top: -0.6em; }

/* ---------- buttons ---------- */
.btn {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 9px 16px; border-radius: 8px; border: 1px solid var(--line);
  background: var(--surface); color: var(--text); font: inherit; font-weight: 600; font-size: 0.95rem;
  cursor: pointer; text-decoration: none;
}
.btn:hover { border-color: var(--accent); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn.primary:hover { filter: brightness(1.08); }
.btn.ghost { background: transparent; }
.btn.small { padding: 4px 10px; font-size: 0.85rem; }
.btn.on { background: var(--accent); color: #fff; border-color: var(--accent); }
.linkish { background: none; border: 0; padding: 0; color: var(--accent); font: inherit; text-decoration: underline; cursor: pointer; }

/* ---------- overview ---------- */
.hero { padding: 8px 0 8px; }
.hero h1 { font-size: 2.5rem; }
.phase h2 { margin-bottom: 0.1em; }
.phase > p { margin: 0 0 0.8em; }
.cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 12px; }
.card {
  display: flex; flex-direction: column; gap: 4px; padding: 14px 16px;
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius);
  color: var(--text); text-decoration: none; transition: border-color .15s, transform .15s;
}
.card:hover { border-color: var(--accent); transform: translateY(-1px); }
.card.done { opacity: 0.7; }
.card-num { font-size: 0.8rem; font-weight: 700; color: var(--accent); }
.card.done .card-num { color: var(--ok); }
.card-title { font-weight: 650; line-height: 1.3; }
.card-sum { font-size: 0.88rem; color: var(--muted); line-height: 1.45; flex: 1; }
.card-meta { font-size: 0.78rem; margin-top: 4px; }

/* ---------- lesson ---------- */
.goals { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 14px 18px; }
.goals ul { margin: 6px 0 0; padding-left: 1.2em; }
.callout { border-radius: var(--radius); padding: 10px 16px; border-left: 4px solid var(--tone); background: color-mix(in srgb, var(--tone) 9%, var(--surface)); }
.callout.warning { border-left-color: var(--target); background: color-mix(in srgb, var(--target) 12%, var(--surface)); }
.callout.listen { border-left-color: var(--accent); background: var(--accent-soft); }
.lesson-foot { margin-top: 3em; padding-top: 1.5em; border-top: 1px solid var(--line); display: flex; flex-direction: column; align-items: flex-start; gap: 14px; }
.pager { display: flex; justify-content: space-between; gap: 10px; width: 100%; flex-wrap: wrap; }
.pager .btn { max-width: 48%; }

/* ---------- figures ---------- */
.fig { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 12px 14px; margin-left: 0; margin-right: 0; }
.fig-title { font-weight: 650; font-size: 0.95rem; margin-bottom: 6px; }
.fig-bar { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; margin-top: 6px; }
figcaption { font-size: 0.88rem; color: var(--muted); flex: 1 1 260px; }
.fb-scroll { overflow-x: auto; }
svg.fb { max-width: 100%; height: auto; display: block; }
svg.fb { background: none; }
svg .fret { stroke: var(--fret); stroke-width: 1.5; }
svg .nut { stroke: var(--text); stroke-width: 5; }
svg .string { stroke: var(--string); }
svg .inlay { fill: var(--line); }
svg .fretnum { fill: var(--muted); font-size: 11px; text-anchor: middle; font-family: var(--font); }
svg .mute { fill: var(--muted); font-size: 14px; text-anchor: middle; }
svg .open { fill: none; stroke: var(--text); stroke-width: 1.5; }
svg .dot { cursor: pointer; }
svg .dot circle { fill: var(--tone); stroke: var(--surface); stroke-width: 1.5; }
svg .dot text { fill: #fff; font-size: 10.5px; font-weight: 700; text-anchor: middle; dominant-baseline: central; font-family: var(--font); pointer-events: none; }
svg .dot text.small { font-size: 8.5px; }
svg .dot.root circle { fill: var(--root); }
svg .dot.target circle { fill: var(--target); }
svg .dot.target text { fill: #1d1a14; }
svg .dot.dim circle { fill: var(--dim); }
svg .dot.mark circle { fill: none; stroke: var(--accent); stroke-width: 2.5; }
svg .dot.mark text { fill: var(--accent); }
svg .dot.ghost circle { fill: transparent; stroke: var(--line); stroke-dasharray: 2 2; }
svg .dot.ghost:hover circle { fill: var(--accent-soft); stroke: var(--accent); }
svg .dot:focus { outline: none; }
svg .dot:focus circle, svg .dot:hover circle { stroke: var(--text); }

.chord-row { display: flex; flex-wrap: wrap; gap: 8px; }
.chordbox {
  background: none; border: 1px solid transparent; border-radius: 8px; padding: 6px 4px 4px; cursor: pointer;
  color: var(--text); font: inherit; display: flex; flex-direction: column; align-items: center; width: 158px;
}
.chordbox:hover { border-color: var(--line); background: var(--surface-2); }
.chord-name { font-weight: 700; font-size: 0.95rem; }
.chord-note { font-size: 0.78rem; color: var(--muted); text-align: center; line-height: 1.3; }
svg.chord { width: 150px; height: auto; }
svg.chord .dot circle { stroke-width: 1; }

.prog { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); border-left: 2px solid var(--text); }
.prog-bar { border-right: 2px solid var(--text); border-bottom: 1px solid var(--line); min-height: 72px; display: flex; flex-direction: column; }
.prog-num { font-size: 0.7rem; color: var(--muted); padding: 4px 10px 0; text-transform: uppercase; letter-spacing: 0.06em; }
.prog-cells { display: flex; flex: 1; }
.prog-cell { flex: 1 1 0; padding: 8px 10px; min-width: 0; overflow-wrap: anywhere; }
.split .prog-cell { padding: 8px 6px; }
.split .prog-chord { font-size: 1rem; }
.prog-cell + .prog-cell { border-left: 1px dashed var(--line); }
.prog-cell.hl { background: var(--accent-soft); }
.prog-chord { font-weight: 700; font-size: 1.1rem; }
.prog-roman { font-family: Georgia, "Times New Roman", serif; font-size: 0.88rem; color: var(--accent); }
.prog-scale { font-size: 0.82rem; }
.prog-tones { font-size: 0.78rem; color: var(--muted); font-family: var(--mono); }

/* ---------- exercises, quiz, drill ---------- */
.exercise, .quiz, .drill, .resources {
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 14px 18px;
}
.exercise.done { border-color: var(--ok); background: color-mix(in srgb, var(--ok) 6%, var(--surface)); }
.ex-head { display: flex; align-items: center; flex-wrap: wrap; gap: 10px; margin-bottom: 4px; }
.ex-head h3 { flex: 1 1 200px; }
.ex-tag { font-size: 0.7rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em; padding: 2px 8px; border-radius: 99px; background: var(--accent-soft); color: var(--accent); }
.quiz-tag { background: color-mix(in srgb, var(--tone) 18%, var(--surface)); color: var(--tone); }
.drill-tag { background: color-mix(in srgb, var(--target) 22%, var(--surface)); color: color-mix(in srgb, var(--target) 60%, var(--text)); }
.steps { padding-left: 1.3em; margin: 8px 0; }
.steps li { margin: 4px 0; }
.ex-done { display: flex; align-items: flex-start; gap: 10px; margin-top: 10px; padding-top: 10px; border-top: 1px dashed var(--line); cursor: pointer; font-size: 0.93rem; }
.ex-done input { width: 18px; height: 18px; margin-top: 3px; accent-color: var(--ok); flex: none; }

.q { margin: 10px 0 16px; }
.q-text { margin: 0 0 8px; font-weight: 550; }
.q-opts, .drill-answers { display: flex; flex-wrap: wrap; gap: 6px; }
.opt {
  padding: 6px 12px; border: 1px solid var(--line); border-radius: 8px; background: var(--bg); color: var(--text);
  font: inherit; font-size: 0.92rem; cursor: pointer;
}
.opt:hover { border-color: var(--accent); }
.opt.right { background: var(--ok-soft); border-color: var(--ok); }
.opt.wrong { background: var(--bad-soft); border-color: var(--bad); }
.q-fb { margin-top: 8px; font-size: 0.92rem; }
.q-fb.ok b { color: var(--ok); }
.q-fb.no b { color: var(--bad); }
.drill-prompt { font-weight: 600; margin: 8px 0 4px; }
.drill-answers { margin-top: 8px; }
.drill-score { margin-top: 10px; font-size: 0.92rem; min-height: 1.5em; }
.drill-ctl { display: flex; gap: 8px; margin-top: 8px; }
.resources ul { margin: 8px 0 0; padding-left: 1.2em; }
.resources li { margin: 4px 0; }

/* ---------- mobile ---------- */
@media (max-width: 860px) {
  .menu-btn { display: inline-flex; }
  .layout { display: block; }
  .sidebar {
    position: fixed; top: 56px; left: 0; bottom: 0; width: min(320px, 86vw); height: auto; z-index: 15;
    background: var(--bg); transform: translateX(-100%); transition: transform .2s;
  }
  body.nav-open .sidebar { transform: none; box-shadow: 0 0 30px rgba(0,0,0,.25); }
  .page { padding: 20px 16px 60px; }
  h1, .hero h1 { font-size: 1.75rem; }
  .pager .btn { max-width: 100%; }
  .prog { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 480px) {
  .metro label { display: none; }
}