/* Lesson kit styles. Shared by the H2 lesson apps. Copy as is; do not edit per app.
   Tokens first, then layout (top bar, home, lesson: stage + cards), then controls. */

:root {
  color-scheme: light;
  --bg: #f6f5f1;
  --card: #ffffff;
  --ink: #1d1f24;
  --muted: #5c6270;
  --line: #d9d6cc;
  --accent: #1f5fbf;
  --accent-ink: #ffffff;
  --accent-soft: #e3ecfa;
  --correct: #1b7a3d;
  --correct-soft: #e2f3e7;
  --wrong: #b3261e;
  --wrong-soft: #fbe7e5;
  --focus: #d97706;
  --stage: #eceae3;
  /* series colours for graphs and models: blue, orange, green, purple, red, teal */
  --s1: #1f5fbf;
  --s2: #d9730d;
  --s3: #2e8b57;
  --s4: #7b4fc4;
  --s5: #c2362f;
  --s6: #138a8a;
  --font: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --radius: 10px;
  --top-h: 48px;
  --tap: 44px;
  --pad: 16px;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    color-scheme: dark;
    --bg: #15171c; --card: #1f2229; --ink: #e8e9ec; --muted: #a2a8b5; --line: #343843;
    --accent: #7aa7ff; --accent-ink: #0d1424; --accent-soft: #24324d;
    --correct: #5cc98a; --correct-soft: #1a3326; --wrong: #ff8a80; --wrong-soft: #3d1f1d;
    --focus: #fbbf24; --stage: #1a1d23;
    --s1: #7aa7ff; --s2: #ffa94d; --s3: #69db7c; --s4: #b197fc; --s5: #ff8787; --s6: #3bc9db;
  }
}
:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #15171c; --card: #1f2229; --ink: #e8e9ec; --muted: #a2a8b5; --line: #343843;
  --accent: #7aa7ff; --accent-ink: #0d1424; --accent-soft: #24324d;
  --correct: #5cc98a; --correct-soft: #1a3326; --wrong: #ff8a80; --wrong-soft: #3d1f1d;
  --focus: #fbbf24; --stage: #1a1d23;
  --s1: #7aa7ff; --s2: #ffa94d; --s3: #69db7c; --s4: #b197fc; --s5: #ff8787; --s6: #3bc9db;
}

*, *::before, *::after { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  background: var(--bg); color: var(--ink);
  font: 16px/1.5 var(--font);
  -webkit-text-size-adjust: 100%;
}
a { color: var(--accent); }
button, input, select { font: inherit; color: inherit; }
:focus-visible { outline: 3px solid var(--focus); outline-offset: 2px; }
.kit-sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
.kit-stage [hidden] { display: none !important; }
.kit-skip { position: absolute; left: -999px; top: 4px; background: var(--card); padding: 8px 12px; z-index: 10; }
.kit-skip:focus { left: 8px; }

/* ---------- top bar ---------- */
.kit-top {
  position: sticky; top: 0; z-index: 5;
  display: flex; align-items: center; gap: 12px;
  height: var(--top-h); padding: 0 var(--pad);
  background: var(--card); border-bottom: 1px solid var(--line);
}
.kit-subject { font-weight: 700; text-decoration: none; color: var(--ink); white-space: nowrap;
  min-height: var(--tap); display: inline-flex; align-items: center; }
.kit-title { flex: 1 1 auto; min-width: 0; font-weight: 600; color: var(--muted);
  overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.kit-dots { display: flex; gap: 6px; align-items: center; flex: none; }
.kit-dot { width: 10px; height: 10px; border-radius: 50%; background: var(--line); }
.kit-dot.is-done { background: var(--accent); opacity: .5; }
.kit-dot.is-now { background: var(--accent); opacity: 1; transform: scale(1.3); }
.kit-theme { flex: none; width: 36px; height: 36px; border-radius: 50%;
  border: 1px solid var(--line); background: transparent; cursor: pointer; line-height: 0; display: inline-flex; align-items: center; justify-content: center; }

/* ---------- home ---------- */
.kit-home { max-width: 760px; margin: 0 auto; padding: 20px 16px 48px; }
.kit-home h1 { font-size: 1.7rem; line-height: 1.2; margin: 8px 0 6px; }
.kit-home .kit-lead { color: var(--muted); margin: 0 0 18px; }
.kit-home h2 { font-size: 1rem; text-transform: uppercase; letter-spacing: .04em; color: var(--muted); margin: 26px 0 8px; }
.kit-list { list-style: none; margin: 0; padding: 0; display: grid; gap: 8px; }
.kit-item a { display: flex; gap: 12px; align-items: center; min-height: 56px; padding: 10px 14px;
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  text-decoration: none; color: var(--ink); }
.kit-item a:hover { border-color: var(--accent); }
.kit-tick { flex: none; width: 26px; height: 26px; border-radius: 50%; border: 2px solid var(--line);
  display: inline-flex; align-items: center; justify-content: center; font-size: 15px; color: transparent; }
.kit-item.is-done .kit-tick { background: var(--correct); border-color: var(--correct); color: var(--card); }
.kit-item-text { display: flex; flex-direction: column; min-width: 0; }
.kit-item-title { font-weight: 600; }
.kit-item-sub { color: var(--muted); font-size: .9rem; }
.kit-review-link { display: inline-flex; align-items: center; min-height: var(--tap); padding: 8px 16px;
  border-radius: var(--radius); background: var(--accent); color: var(--accent-ink); text-decoration: none; font-weight: 600; }
.kit-note { color: var(--muted); font-size: .9rem; }

/* ---------- lesson: stage + cards ---------- */
.kit-lesson {
  display: grid; grid-template-columns: minmax(0, 1fr) minmax(320px, 420px);
  height: calc(100vh - var(--top-h)); height: calc(100dvh - var(--top-h));
}
.kit-stage { position: relative; display: flex; flex-direction: column; min-width: 0; min-height: 0;
  background: var(--stage); border-right: 1px solid var(--line); }
.kit-tabs-slot { flex: none; }
.kit-tabs-slot:empty { display: none; }
.kit-tabs { display: flex; gap: 0; padding: 0 var(--pad); background: var(--card); border-bottom: 1px solid var(--line); overflow-x: auto; scrollbar-width: none; }
.kit-tab { flex: none; min-height: var(--tap); padding: 0 14px; border: 0; border-bottom: 3px solid transparent; margin-bottom: -1px;
  background: none; color: var(--muted); font-weight: 600; cursor: pointer; white-space: nowrap; }
.kit-tab:hover { color: var(--ink); }
.kit-tab[aria-selected="true"] { color: var(--accent); border-bottom-color: var(--accent); }
.kit-view { position: relative; flex: 1 1 auto; min-height: 0; overflow: hidden; }
.kit-view > canvas, .kit-view > svg { display: block; width: 100%; height: 100%; touch-action: none; }
/* The control panel: labelled rows (label column, widget column) packed two across when wide; loose buttons flow. */
.kit-controls { flex: none; display: flex; flex-wrap: wrap; gap: 8px 20px; align-items: center;
  padding: 10px var(--pad); border-top: 1px solid var(--line); background: var(--card); max-height: 45%; overflow-y: auto; }
.kit-row { flex: 1 1 340px; max-width: 100%; min-width: 0; display: grid; grid-template-columns: var(--label-w, 7em) minmax(0, 1fr);
  align-items: center; gap: 6px 10px; }
.kit-row.is-unlabelled { grid-template-columns: minmax(0, 1fr); }
.kit-row-label { font-size: .88rem; color: var(--muted); line-height: 1.25; overflow-wrap: anywhere; }
.kit-row-body { display: flex; align-items: center; gap: 8px; min-width: 0; }
.kit-row-body > * { max-width: 100%; }
.kit-controls:empty, .kit-controls:not(:has(> :not([hidden]))) { display: none; }
/* phone only: a thin bar that opens and closes the controls */
.kit-ctl-toggle { display: none; }
.kit-cards { display: flex; flex-direction: column; min-height: 0; background: var(--bg); }
.kit-card-scroll { flex: 1 1 auto; overflow-y: auto; padding: var(--pad); }
.kit-card { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 16px 18px; }
.kit-card h2 { font-size: 1.15rem; line-height: 1.3; margin: 0 0 8px; }
.kit-card p { margin: 0 0 10px; }
.kit-card p:last-child { margin-bottom: 0; }
.kit-kind { font-size: .78rem; text-transform: uppercase; letter-spacing: .06em; color: var(--accent); font-weight: 700; margin-bottom: 4px; }
.kit-ref { font-size: .82rem; color: var(--muted); }
.kit-nav { flex: none; display: flex; gap: 10px; padding: 10px var(--pad); border-top: 1px solid var(--line); background: var(--card); }
.kit-nav .kit-btn { flex: 1; }
.kit-loading { padding: 20px; color: var(--muted); }

/* questions */
.kit-q { font-weight: 600; margin: 0 0 10px; }
.kit-options { display: grid; gap: 8px; margin: 0 0 10px; }
.kit-option { text-align: left; min-height: var(--tap); padding: 10px 12px; border-radius: 8px;
  border: 1px solid var(--line); background: var(--bg); cursor: pointer; line-height: 1.35; }
.kit-option:hover:not(:disabled) { border-color: var(--accent); }
.kit-option[aria-pressed="true"] { border-color: var(--accent); background: var(--accent-soft); }
.kit-option.is-right { border-color: var(--correct); background: var(--correct-soft); }
.kit-option.is-wrong { border-color: var(--wrong); background: var(--wrong-soft); }
.kit-option:disabled { cursor: default; color: var(--ink); }
.kit-why { display: block; font-size: .9rem; color: var(--muted); margin-top: 4px; }
.kit-feedback { border-left: 4px solid var(--line); padding: 6px 10px; margin: 8px 0; border-radius: 4px; background: var(--bg); }
.kit-feedback.is-right { border-color: var(--correct); }
.kit-feedback.is-wrong { border-color: var(--wrong); }
.kit-verdict { font-weight: 700; }
.kit-feedback.is-right .kit-verdict { color: var(--correct); }
.kit-feedback.is-wrong .kit-verdict { color: var(--wrong); }
.kit-count { font-size: .85rem; color: var(--muted); margin-bottom: 6px; }

/* worked example */
.kit-lines { margin: 0 0 12px; padding-left: 1.6em; }
.kit-lines li { margin: 0 0 4px; }
.kit-lines .kit-blank-line { background: var(--accent-soft); border-radius: 6px; padding: 4px 6px; }
.kit-lines select, .kit-lines input { min-height: var(--tap); padding: 6px 8px; border-radius: 6px;
  border: 1px solid var(--line); background: var(--card); max-width: 100%; }
.kit-lines input { width: 9em; }
.kit-sub { font-weight: 600; margin: 12px 0 6px; }

/* ---------- controls ---------- */
.kit-btn { min-height: var(--tap); padding: 8px 14px; border-radius: 8px; border: 1px solid var(--line);
  background: var(--card); cursor: pointer; font-weight: 600; }
.kit-btn:hover:not(:disabled) { border-color: var(--accent); }
.kit-btn.is-primary { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
.kit-btn:disabled { opacity: .45; cursor: not-allowed; }
.kit-btn[aria-pressed="true"] { background: var(--accent-soft); border-color: var(--accent); }
.kit-slider input[type=range] { flex: 1 1 auto; min-width: 0; min-height: var(--tap); accent-color: var(--accent); margin: 0; }
.kit-slider output { flex: none; min-width: 3.5em; text-align: right; font-size: .88rem; font-variant-numeric: tabular-nums; font-weight: 700; }
.kit-seg { display: inline-flex; flex-wrap: wrap; max-width: 100%; border: 1px solid var(--line); border-radius: 8px; background: var(--card); overflow: hidden; }
.kit-seg-btn { min-height: calc(var(--tap) - 2px); padding: 6px 12px; border: 0; border-right: 1px solid var(--line); background: none;
  color: var(--muted); font-weight: 600; cursor: pointer; white-space: nowrap; }
.kit-seg-btn:last-child { border-right: 0; }
.kit-seg-btn:hover { color: var(--ink); }
.kit-seg-btn[aria-pressed="true"] { background: var(--accent-soft); color: var(--accent); }
.kit-select { min-height: var(--tap); padding: 6px 8px; border-radius: 8px; border: 1px solid var(--line); background: var(--card); max-width: 100%; flex: 1 1 auto; min-width: 0; }
.kit-readout { font-variant-numeric: tabular-nums; font-size: .88rem; color: var(--muted); }
.kit-readout span { color: var(--ink); font-weight: 700; }
/* a free-form row of buttons, for lessons that build their own controls */
.kit-group { display: flex; flex-wrap: wrap; gap: 6px; align-items: center; }
.kit-overlay { position: absolute; left: 8px; top: 8px; display: flex; flex-direction: column; gap: 4px; pointer-events: none; font-size: .9rem; }
.kit-overlay > * { pointer-events: auto; background: color-mix(in srgb, var(--card) 85%, transparent); padding: 3px 8px; border-radius: 6px; width: max-content; max-width: calc(100% - 16px); }
.kit-corner { position: absolute; right: 8px; top: 8px; display: flex; gap: 6px; }
.kit-3dlabel { position: absolute; transform: translate(-50%, -50%); font: 600 13px var(--font); color: var(--ink);
  background: color-mix(in srgb, var(--card) 80%, transparent); padding: 1px 5px; border-radius: 5px; pointer-events: none; white-space: nowrap; }

/* review */
.kit-review { max-width: 640px; margin: 0 auto; padding: 20px 16px 48px; }
.kit-review .kit-card { margin-top: 12px; }

/* ---------- phone ----------
   The page itself scrolls, so the browser's own bar folds away. The top bar is thin, the stage sticks under it
   and gets shorter on question steps, the controls wrap and fold behind a toggle, Back and Next stick to the bottom. */
.kit-lesson-head { display: none; font-weight: 600; margin: 0 0 8px; color: var(--muted); font-size: .9rem; }

@media (max-width: 760px) {
  :root { --top-h: 40px; --pad: 12px; }
  .kit-top { gap: 10px; }
  .kit-subject { font-size: .9rem; min-height: 0; }
  .kit-title { display: none; }
  .kit-dots { flex: 1; gap: 3px; }
  .kit-dot { flex: 1; width: auto; height: 4px; border-radius: 2px; }
  .kit-dot.is-now { transform: none; }
  .kit-theme { width: 32px; height: 32px; }
  .kit-theme svg { width: 18px; height: 18px; }
  .kit-lesson { display: flex; flex-direction: column; height: auto; min-height: calc(100vh - var(--top-h)); min-height: calc(100dvh - var(--top-h)); }
  .kit-stage { position: sticky; top: var(--top-h); z-index: 4; flex: none; height: auto; border-right: 0; border-bottom: 1px solid var(--line); }
  .kit-view { flex: none; height: 38vh; height: 38dvh; }
  .kit-lesson[data-step="predict"] .kit-view, .kit-lesson[data-step="worked"] .kit-view,
  .kit-lesson[data-step="check"] .kit-view, .kit-lesson[data-step="reveal"] .kit-view { height: 26vh; height: 26dvh; }
  .kit-ctl-toggle { display: flex; align-items: center; justify-content: center; gap: 6px; width: 100%; min-height: 32px;
    padding: 0; border: 0; border-top: 1px solid var(--line); background: var(--card); color: var(--muted);
    font-size: .8rem; font-weight: 600; text-transform: uppercase; letter-spacing: .05em; cursor: pointer; }
  .kit-ctl-toggle::after { content: ""; width: 7px; height: 7px; border: solid currentColor; border-width: 0 2px 2px 0;
    transform: translateY(-2px) rotate(45deg); }
  .kit-stage.is-open .kit-ctl-toggle::after { transform: translateY(2px) rotate(-135deg); }
  .kit-stage:not(:has(.kit-controls > :not([hidden]))) .kit-ctl-toggle { display: none; }
  .kit-stage:not(.is-open) .kit-controls { display: none; }
  .kit-controls { max-height: 34vh; max-height: 34dvh; padding: 8px var(--pad) 10px; gap: 8px 12px; }
  .kit-controls .kit-btn { min-height: 38px; padding: 6px 12px; }
  .kit-row { flex-basis: 100%; --label-w: 5.5em; }
  .kit-seg-btn { min-height: 36px; padding: 5px 10px; }
  .kit-tabs { padding: 0 4px; }
  .kit-tab { flex: 1 1 0; min-width: 0; min-height: 40px; padding: 4px 6px; font-size: .85rem; line-height: 1.15; white-space: normal; }
  .kit-overlay { font-size: .78rem; gap: 2px; left: 4px; top: 4px; right: 112px; }
  .kit-overlay > * { padding: 1px 6px; max-width: 100%; }
  .kit-corner .kit-btn { padding: 6px 10px; }
  .kit-cards { flex: 1 1 auto; }
  .kit-card-scroll { flex: 1 1 auto; overflow: visible; }
  .kit-card { padding: 12px 14px; }
  .kit-nav { position: sticky; bottom: 0; z-index: 3; padding: 6px var(--pad); gap: 8px;
    padding-bottom: max(6px, env(safe-area-inset-bottom)); }
  .kit-nav .kit-btn { min-height: 40px; }
  .kit-nav .kit-btn:not(.is-primary) { flex: 0 0 auto; padding: 6px 18px; }
  .kit-lesson-head { display: block; }
}
@media (prefers-reduced-motion: reduce) { * { transition: none !important; animation: none !important; } }