/* ============================================================================
   Dialled In — shared stylesheet
   One look for every page. Tufte-inspired typography on warm paper, a single
   accent hue, green/red for right-vs-wrong, and reusable component classes
   (callouts, source boxes, quizzes, before/after pairs, fault-finders).
   Linked by index.html and every lesson. No external fonts — works offline.
   Structure is identical across every course in this workspace; only the
   accent hue changes, so the courses read as one studio.
   ============================================================================ */

:root {
  /* Palette — warm paper, one accent hue, green/red for right vs wrong */
  --paper:      #fbfaf6;
  --paper-2:    #f1efe6;
  --ink:        #1b1a22;
  --ink-soft:   #4a4954;
  --ink-faint:  #7a7986;
  --rule:       #ddd9cc;

  --accent:      #c2410c;   /* primary accent */
  --accent-deep: #7c2d12;   /* headings, links */
  --dark:        #1b1210;   /* darkest — code bg, hero */
  --bright:      #fb923c;   /* bright highlight on dark */
  --bad:        #c0392b;   /* wrong / warning / before */
  --good:       #2f7d4e;   /* correct / go / after */
  --gold:       #b98a1e;   /* key insight / highlight */

  --maxw:       46rem;     /* measure for body text */
  --gutter:     clamp(1rem, 4vw, 3rem);

  --serif: "Iowan Old Style", "Palatino Linotype", Palatino, "Book Antiqua", Georgia, serif;
  --sans:  "Inter", "Helvetica Neue", -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, sans-serif;
  --mono:  "SF Mono", "JetBrains Mono", "Fira Mono", ui-monospace, "Menlo", monospace;

  --shadow: 0 1px 2px rgba(26,24,48,.06), 0 6px 22px rgba(26,24,48,.08);
  --radius: 10px;
}

/* ---- Reset-ish ---------------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--serif);
  font-size: clamp(1.02rem, 0.55rem + 0.9vw, 1.2rem);
  line-height: 1.62;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}
img, svg, canvas { max-width: 100%; height: auto; }

/* ---- Layout ------------------------------------------------------------- */
.wrap { max-width: var(--maxw); margin-inline: auto; padding-inline: var(--gutter); }
.wrap-wide { max-width: 64rem; margin-inline: auto; padding-inline: var(--gutter); }
main { padding-block: 1rem 4rem; }
section { margin-block: 2.4rem; }

/* ---- Top bar (identical on every page) ---------------------------------- */
.topbar {
  background: linear-gradient(180deg, var(--dark), var(--accent-deep));
  color: #ecebfa;
  border-bottom: 3px solid var(--accent);
}
.topbar .wrap-wide { display: flex; align-items: center; justify-content: space-between; gap: 1rem; padding-block: .7rem; }
.topbar a { color: #d7d5f4; text-decoration: none; }
.topbar .brand { font-family: var(--mono); font-weight: 700; letter-spacing: .01em; display: flex; align-items: center; gap: .5rem; }
.topbar .brand .dot { color: var(--bright); }
.topbar nav { font-family: var(--sans); font-size: .82rem; display: flex; gap: 1.1rem; }
.topbar nav a:hover { color: #fff; text-decoration: underline; }

/* ---- Lesson header ------------------------------------------------------ */
.kicker {
  font-family: var(--sans);
  text-transform: uppercase;
  letter-spacing: .14em;
  font-size: .72rem;
  font-weight: 700;
  color: var(--accent);
}
.lesson-title { font-family: var(--serif); font-weight: 600; font-size: clamp(1.9rem, 1rem + 3vw, 3rem); line-height: 1.08; margin: .35rem 0 .3rem; color: var(--accent-deep); }
.lesson-sub { font-size: 1.18rem; color: var(--ink-soft); font-style: italic; margin: 0 0 1rem; }
.lesson-meta { font-family: var(--sans); font-size: .78rem; color: var(--ink-faint); display: flex; flex-wrap: wrap; gap: .4rem .9rem; align-items: center; border-block: 1px solid var(--rule); padding-block: .55rem; margin-block: 1.1rem 2rem; }
.lesson-meta .sep { color: var(--rule); }

/* ---- Headings & text ---------------------------------------------------- */
h2 { font-family: var(--serif); font-weight: 600; font-size: 1.6rem; line-height: 1.2; margin: 2.6rem 0 .7rem; color: var(--accent-deep); }
h2 .num { color: var(--bright); font-variant-numeric: tabular-nums; margin-right: .4rem; }
h3 { font-family: var(--sans); font-weight: 700; font-size: 1.04rem; letter-spacing: .01em; margin: 1.8rem 0 .5rem; color: var(--accent-deep); }
p { margin: 0 0 1.05rem; }
.lead { font-size: 1.2rem; color: var(--ink-soft); }
a { color: var(--accent-deep); text-decoration-color: color-mix(in srgb, var(--accent) 40%, transparent); text-underline-offset: 2px; }
a:hover { text-decoration-color: var(--accent); }
strong { color: var(--accent-deep); }
em { color: inherit; }
hr { border: 0; border-top: 1px solid var(--rule); margin: 2.4rem 0; }
ul, ol { padding-left: 1.3rem; }
li { margin: .3rem 0; }
li::marker { color: var(--accent); }
small { font-size: .82em; color: var(--ink-faint); }
sup { line-height: 0; }

/* ---- Citations / reference superscripts --------------------------------- */
.cite { font-family: var(--sans); font-size: .62em; font-weight: 700; vertical-align: super; }
.cite a { text-decoration: none; padding: 0 .15em; color: var(--accent); }
.cite a:hover { text-decoration: underline; }

/* ---- Sidenotes / margin notes ------------------------------------------- */
.sidenote { font-family: var(--sans); font-size: .82rem; line-height: 1.45; color: var(--ink-soft); border-left: 3px solid var(--rule); padding: .1rem 0 .1rem .8rem; margin: 1.1rem 0; }

/* ---- Figures ------------------------------------------------------------ */
figure { margin: 1.8rem 0; }
figcaption { font-family: var(--sans); font-size: .8rem; color: var(--ink-faint); margin-top: .55rem; line-height: 1.45; }
figcaption b { color: var(--ink-soft); }
.frame { background: #fff; border: 1px solid var(--rule); border-radius: var(--radius); padding: 1rem; box-shadow: var(--shadow); }

/* ---- Callouts ----------------------------------------------------------- */
.callout { border-radius: var(--radius); padding: 1rem 1.15rem 1.05rem; margin: 1.6rem 0; border: 1px solid var(--rule); background: #fff; box-shadow: var(--shadow); position: relative; }
.callout > .callout-label { font-family: var(--sans); font-weight: 700; font-size: .72rem; text-transform: uppercase; letter-spacing: .1em; display: flex; align-items: center; gap: .45rem; margin-bottom: .4rem; }
.callout p:last-child { margin-bottom: 0; }
.callout.key      { border-left: 5px solid var(--gold);   background: #fffdf3; }
.callout.key      .callout-label { color: #8a6813; }
.callout.note     { border-left: 5px solid var(--accent); background: color-mix(in srgb, var(--accent) 7%, #fff); }
.callout.note     .callout-label { color: var(--accent-deep); }
.callout.mission  { border-left: 5px solid var(--bright); background: color-mix(in srgb, var(--accent) 10%, #fff); }
.callout.mission  .callout-label { color: var(--accent-deep); }
.callout.build    { border-left: 5px solid var(--good);   background: #f1faf3; }
.callout.build    .callout-label { color: var(--good); }
.callout.warning  { border-left: 5px solid var(--bad);    background: #fdf2f0; }
.callout.warning  .callout-label { color: var(--bad); }

/* ---- Primary source box ------------------------------------------------- */
.sourcebox { display: flex; gap: .9rem; align-items: flex-start; background: linear-gradient(180deg, color-mix(in srgb, var(--accent) 7%, #fff), #fff); border: 1px solid var(--rule); border-top: 4px solid var(--accent); border-radius: var(--radius); padding: 1rem 1.15rem; margin: 1.8rem 0; box-shadow: var(--shadow); }
.sourcebox .icon { font-size: 1.5rem; line-height: 1.2; }
.sourcebox .label { font-family: var(--sans); font-weight: 700; font-size: .7rem; text-transform: uppercase; letter-spacing: .1em; color: var(--accent); margin-bottom: .2rem; }
.sourcebox .title { font-weight: 600; }
.sourcebox .desc { font-family: var(--sans); font-size: .84rem; color: var(--ink-soft); margin-top: .2rem; }

/* ---- "Ask your tutor" reminder ------------------------------------------ */
.ask-teacher { font-family: var(--sans); font-size: .9rem; background: var(--paper-2); border: 1px dashed var(--accent); border-radius: var(--radius); padding: .9rem 1.1rem; margin: 2rem 0; color: var(--ink-soft); }
.ask-teacher b { color: var(--accent-deep); }

/* ---- Tables ------------------------------------------------------------- */
table { border-collapse: collapse; width: 100%; margin: 1.6rem 0; font-size: .92rem; font-family: var(--sans); }
caption { font-family: var(--sans); font-size: .8rem; color: var(--ink-faint); text-align: left; margin-bottom: .5rem; }
th, td { text-align: left; padding: .55rem .7rem; border-bottom: 1px solid var(--rule); vertical-align: top; }
thead th { border-bottom: 2px solid var(--ink-soft); font-size: .76rem; text-transform: uppercase; letter-spacing: .06em; color: var(--ink-soft); }
tbody tr:hover { background: var(--paper-2); }
td.num, th.num { text-align: right; font-variant-numeric: tabular-nums; }

/* ---- Tags / pills ------------------------------------------------------- */
.tag { display: inline-block; font-family: var(--sans); font-size: .68rem; font-weight: 700; text-transform: uppercase; letter-spacing: .06em; padding: .15rem .5rem; border-radius: 999px; background: var(--paper-2); color: var(--ink-soft); border: 1px solid var(--rule); }
.tag.accent { background: color-mix(in srgb, var(--accent) 10%, #fff); color: var(--accent-deep); border-color: color-mix(in srgb, var(--accent) 30%, #fff); }
.tag.build  { background: #eef7ef; color: var(--good); border-color: #cfe6d3; }
.tag.warn   { background: #fdf6e3; color: #8a6813; border-color: #ecdcae; }

/* ---- Code --------------------------------------------------------------- */
pre, code { font-family: var(--mono); }
code { background: var(--paper-2); padding: .08em .35em; border-radius: 4px; font-size: .9em; color: var(--accent-deep); }
pre { background: var(--dark); color: #e7e6fb; padding: 1rem 1.2rem; border-radius: var(--radius); overflow-x: auto; line-height: 1.6; font-size: .86rem; box-shadow: var(--shadow); }
pre code { background: none; padding: 0; color: inherit; font-size: 1em; }
/* lightweight token tints for hand-marked snippets */
pre .c  { color: #8a88b3; font-style: italic; }   /* comment */
pre .k  { color: #b3a0ff; }                        /* keyword */
pre .s  { color: #9ce0b0; }                        /* string */
pre .f  { color: #86c5ff; }                        /* function/name */
pre .n  { color: #ffce87; }                        /* number/constant */
pre .hl { background: rgba(192,57,43,.25); border-radius: 3px; padding: 0 .15em; }   /* mark a problem */
pre .ok { background: rgba(47,125,78,.28); border-radius: 3px; padding: 0 .15em; }   /* mark a fix */

/* ---- Before / after pair ------------------------------------------------ */
.compare { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; margin: 1.4rem 0; }
@media (max-width: 40rem) { .compare { grid-template-columns: 1fr; } }
.compare figure { margin: 0; display: flex; flex-direction: column; min-width: 0; }
.compare .difflabel { font-family: var(--sans); font-size: .72rem; font-weight: 800; letter-spacing: .07em; text-transform: uppercase; padding: .35rem .2rem; display: flex; align-items: center; gap: .4rem; }
.compare .before .difflabel { color: var(--bad); }
.compare .after  .difflabel { color: var(--good); }
.compare .before .difflabel::before { content: "✗"; }
.compare .after  .difflabel::before { content: "✓"; }
.compare .before pre { border-top: 3px solid var(--bad); }
.compare .after  pre { border-top: 3px solid var(--good); }
.compare pre { margin: 0; flex: 1 1 auto; }   /* fill the figure below the label — no height:100% overflow */

/* single standalone code figure */
.codefig { margin: 1.4rem 0; }
.codefig .difflabel { font-family: var(--sans); font-size: .72rem; font-weight: 800; letter-spacing: .07em; text-transform: uppercase; color: var(--ink-faint); padding: .35rem .2rem; }

/* ===========================================================================
   INTERACTIVE WIDGETS  (paired with assets/widgets.js)
   =========================================================================== */

/* ---- Quiz --------------------------------------------------------------- */
.quiz { background: #fff; border: 1px solid var(--rule); border-radius: var(--radius); padding: 1.2rem 1.25rem 1.3rem; margin: 1.8rem 0; box-shadow: var(--shadow); }
.quiz .q-kicker { font-family: var(--sans); font-size: .68rem; font-weight: 700; letter-spacing: .12em; text-transform: uppercase; color: var(--accent); }
.quiz .q-text { font-weight: 600; font-size: 1.12rem; margin: .35rem 0 .9rem; color: var(--accent-deep); }
.quiz .q-text code { font-size: .85em; }
.quiz .q-options { display: grid; gap: .55rem; }
.quiz button.opt {
  font-family: var(--sans); font-size: .95rem; text-align: left; cursor: pointer;
  background: var(--paper); border: 1.5px solid var(--rule); border-radius: 8px;
  padding: .7rem .9rem; color: var(--ink); transition: border-color .15s, background .15s, transform .05s;
}
.quiz button.opt code { font-size: .88em; background: rgba(0,0,0,.05); }
.quiz button.opt:hover { border-color: var(--accent); }
.quiz button.opt:active { transform: translateY(1px); }
.quiz button.opt.correct { border-color: var(--good); background: #eef7ef; color: #245c30; font-weight: 600; }
.quiz button.opt.wrong   { border-color: var(--bad);  background: #fdf0ec; color: #8d2f1a; }
.quiz button.opt:disabled { cursor: default; opacity: .9; }
.quiz .q-feedback { font-family: var(--sans); font-size: .9rem; margin-top: .85rem; padding: .7rem .85rem; border-radius: 8px; display: none; line-height: 1.5; }
.quiz .q-feedback.show { display: block; }
.quiz .q-feedback.right { background: #eef7ef; color: #245c30; border: 1px solid #cfe6d3; }
.quiz .q-feedback.nope  { background: #fdf0ec; color: #8d2f1a; border: 1px solid #f0cfc4; }

/* ---- Task box (hands-on, paste back to the tutor) ----------------------- */
.task { background: linear-gradient(180deg, #fff, color-mix(in srgb, var(--accent) 5%, #fff)); border: 2px dashed var(--accent); border-radius: var(--radius); padding: 1.2rem 1.3rem; margin: 1.9rem 0; box-shadow: var(--shadow); }
.task .task-label { font-family: var(--sans); font-weight: 700; font-size: .72rem; text-transform: uppercase; letter-spacing: .1em; color: var(--accent); margin-bottom: .3rem; }
.task h3 { margin-top: .1rem; }
.task .go { font-family: var(--sans); font-size: .95rem; font-weight: 600; color: var(--accent-deep); }

/* ---- Fault-finder (symptom → why → fix), paired with widgets.js ---------- */
.faultfinder { background:#fff; border:1px solid var(--rule); border-top:4px solid var(--bad); border-radius:var(--radius); padding:1.1rem 1.2rem 1.2rem; margin:1.8rem 0; box-shadow:var(--shadow); }
.faultfinder .ff-q { font-family:var(--sans); font-weight:700; font-size:.92rem; color:var(--accent-deep); margin-bottom:.6rem; }
.ff-list { list-style:none; margin:0; padding:0; display:grid; gap:.4rem; }
.ff-item { font-family:var(--sans); font-size:.9rem; cursor:pointer; padding:.55rem .8rem; border:1.5px solid var(--rule); border-radius:8px; background:var(--paper); color:var(--ink); display:flex; align-items:center; gap:.5rem; transition:border-color .12s, background .12s; }
.ff-item:hover { border-color:var(--accent); }
.ff-item.active { border-color:var(--accent); background:color-mix(in srgb, var(--accent) 10%, #fff); color:var(--accent-deep); font-weight:600; }
.ff-item .ff-tag { margin-left:auto; font-size:.64rem; font-weight:700; text-transform:uppercase; letter-spacing:.05em; padding:.1rem .45rem; border-radius:999px; background:var(--paper-2); color:var(--ink-faint); border:1px solid var(--rule); white-space:nowrap; }
.ff-panel { display:none; margin-top:.9rem; border-top:1px solid var(--rule); padding-top:.9rem; font-family:var(--sans); font-size:.9rem; line-height:1.5; }
.faultfinder.answered .ff-panel { display:block; }
.ff-panel .ff-cause { color:#8d2f1a; margin-bottom:.55rem; }
.ff-panel .ff-fix { color:#245c30; }
.ff-panel .lab { font-weight:700; text-transform:uppercase; font-size:.66rem; letter-spacing:.06em; display:block; margin-bottom:.15rem; }

/* ---- Checklist with live progress tally --------------------------------- */
.checklist-widget { background:#fff; border:1px solid var(--rule); border-top:4px solid var(--good); border-radius:var(--radius); padding:1.1rem 1.2rem 1rem; margin:1.8rem 0; box-shadow:var(--shadow); }
.checklist-widget .cl-title { font-family:var(--sans); font-weight:700; font-size:.95rem; color:var(--accent-deep); margin-bottom:.7rem; display:flex; align-items:center; gap:.5rem; }
.checklist { list-style:none; padding:0; margin:0; display:grid; gap:.45rem; }
.checklist [data-check] { font-family:var(--sans); font-size:.92rem; cursor:pointer; user-select:none; display:flex; align-items:flex-start; gap:.6rem; padding:.55rem .7rem; border:1.5px solid var(--rule); border-radius:8px; background:var(--paper); color:var(--ink); transition:border-color .12s, background .12s, opacity .12s; }
.checklist [data-check]::before { content:"○"; color:var(--ink-faint); font-weight:700; line-height:1.4; }
.checklist [data-check]:hover { border-color:var(--good); }
.checklist [data-check]:focus-visible { outline:2px solid var(--accent); outline-offset:2px; }
.checklist [data-check].done { background:#f1faf3; border-color:#cfe6d3; opacity:.75; text-decoration:line-through; text-decoration-color:var(--ink-faint); }
.checklist [data-check].done::before { content:"●"; color:var(--good); }
.checklist-bar { display:flex; justify-content:space-between; align-items:center; gap:1rem; font-family:var(--sans); font-size:.82rem; font-weight:700; color:var(--ink-soft); margin-top:.8rem; padding-top:.7rem; border-top:1px solid var(--rule); }
.checklist-bar [data-checklist-progress] { color:var(--good); margin-left:auto; }
.cl-reset { font-family:var(--sans); font-size:.72rem; font-weight:700; cursor:pointer; color:var(--ink-faint); background:none; border:1px solid var(--rule); border-radius:999px; padding:.15rem .6rem; }
.cl-reset:hover { color:var(--bad); border-color:var(--bad); }

/* ---- Live calculator (paired with .calc in widgets.js) ------------------ */
[hidden] { display:none !important; }

.calc { background:#fff; border:1px solid var(--rule); border-top:4px solid var(--gold); border-radius:var(--radius); padding:1.1rem 1.2rem 1.15rem; margin:1.8rem 0; box-shadow:var(--shadow); }
.calc .calc-title { font-family:var(--sans); font-weight:700; font-size:.95rem; color:var(--accent-deep); margin-bottom:.2rem; display:flex; align-items:center; gap:.5rem; }
.calc .calc-lede { font-family:var(--sans); font-size:.82rem; color:var(--ink-soft); margin:0 0 .9rem; line-height:1.45; }
.calc-grid { display:grid; grid-template-columns:repeat(auto-fit, minmax(9.5rem, 1fr)); gap:.6rem .8rem; }
.calc-grid.tight { grid-template-columns:repeat(auto-fit, minmax(6rem, 1fr)); }
/* one row per printed wall, so three readings always read as a set */
.calc-grid.walls { grid-template-columns:repeat(3, minmax(0, 1fr)); max-width:28rem; }
/* a value and its measured/inherited mark must never wrap apart */
.calc-grid.pairs { grid-template-columns:repeat(auto-fit, minmax(15rem, 1fr)); }
.calc-pair { display:grid; grid-template-columns:1fr 4.6rem; gap:.5rem; align-items:end; }
.calc-field { font-family:var(--sans); font-size:.72rem; font-weight:700; letter-spacing:.03em; text-transform:uppercase; color:var(--ink-faint); display:flex; flex-direction:column; gap:.25rem; }
.calc-field input, .calc-field select {
  font-family:var(--mono); font-size:.92rem; color:var(--ink); background:var(--paper);
  border:1.5px solid var(--rule); border-radius:8px; padding:.45rem .55rem; width:100%; min-width:0;
}
.calc-field select { font-family:var(--sans); }
.calc-field input[type=range] { padding:0; border:0; background:none; accent-color:var(--accent); height:2.1rem; }
.calc-field input:focus, .calc-field select:focus { outline:none; border-color:var(--accent); background:#fff; }
.calc-field .u { font-weight:600; letter-spacing:0; text-transform:none; color:var(--ink-faint); font-size:.7rem; }

.calc-outs { display:grid; grid-template-columns:repeat(auto-fit, minmax(11rem, 1fr)); gap:.6rem; margin-top:1rem; padding-top:.9rem; border-top:1px solid var(--rule); }
.calc-out { background:var(--paper-2); border-radius:8px; padding:.6rem .75rem; }
.calc-out .lab { display:block; font-family:var(--sans); font-size:.66rem; font-weight:700; letter-spacing:.08em; text-transform:uppercase; color:var(--ink-faint); }
.calc-out .val { font-family:var(--mono); font-size:1.25rem; font-weight:700; color:var(--accent-deep); font-variant-numeric:tabular-nums; line-height:1.3; }
.calc-out .val.pending { color:var(--ink-faint); font-weight:400; }
.calc-out.primary { background:linear-gradient(180deg, color-mix(in srgb, var(--accent) 12%, #fff), #fff); border:1px solid color-mix(in srgb, var(--accent) 25%, #fff); }
.calc-out.primary .val { font-size:1.5rem; color:var(--accent); }

.calc-flag { font-family:var(--sans); font-size:.85rem; line-height:1.5; border-radius:8px; padding:.6rem .8rem; margin-top:.75rem; border-left:4px solid var(--rule); }
.calc-flag b { color:inherit; }
.calc-flag.good { background:#f1faf3; border-left-color:var(--good); color:#245c30; }
.calc-flag.warn { background:#fffdf3; border-left-color:var(--gold); color:#7a5a10; }
.calc-flag.bad  { background:#fdf2f0; border-left-color:var(--bad);  color:#8d2f1a; }

.calc-tpl { font-family:var(--mono); font-size:.8rem; line-height:1.6; background:var(--dark); color:#e7e6fb; border-radius:8px; padding:.8rem .9rem; margin-top:.9rem; overflow-x:auto; white-space:pre; }
.calc-foot { display:flex; align-items:center; gap:.6rem; flex-wrap:wrap; margin-top:.8rem; font-family:var(--sans); font-size:.76rem; color:var(--ink-faint); }
.copy-btn, .calc-foot button {
  font-family:var(--sans); font-size:.76rem; font-weight:700; cursor:pointer;
  background:var(--accent); color:#fff; border:0; border-radius:8px; padding:.42rem .85rem;
}
.copy-btn:hover, .calc-foot button:hover { background:var(--accent-deep); }
.calc-foot button[data-calc-reset] { background:none; color:var(--ink-faint); border:1px solid var(--rule); }
.calc-foot button[data-calc-reset]:hover { background:var(--paper-2); color:var(--ink); }

/* ---- Course progress (injected by widgets.js) --------------------------- */
.lesson-done { display:flex; align-items:center; gap:.8rem; flex-wrap:wrap; margin-top:2.6rem; padding:.9rem 1.1rem; background:var(--paper-2); border:1px solid var(--rule); border-radius:var(--radius); }
.lesson-done.is-done { background:#f1faf3; border-color:#cfe6d3; }
.lesson-done .ld-btn { font-family:var(--sans); font-size:.85rem; font-weight:700; cursor:pointer; background:var(--accent); color:#fff; border:0; border-radius:8px; padding:.5rem 1rem; }
.lesson-done .ld-btn:hover { background:var(--accent-deep); }
.lesson-done.is-done .ld-btn { background:var(--good); }
.lesson-done .ld-note { font-family:var(--sans); font-size:.75rem; color:var(--ink-faint); }

.resume { display:flex; align-items:center; gap:.8rem; flex-wrap:wrap; margin-top:2rem; padding:.85rem 1.1rem; background:#fff; border:1px solid var(--rule); border-left:4px solid var(--good); border-radius:var(--radius); box-shadow:var(--shadow); font-family:var(--sans); }
.resume .rz-lab { font-size:.68rem; font-weight:700; letter-spacing:.1em; text-transform:uppercase; color:var(--ink-faint); }
.resume .rz-count { font-size:.9rem; color:var(--ink-soft); }
.resume .rz-cta { margin-left:auto; font-size:.85rem; font-weight:700; text-decoration:none; color:#fff; background:var(--accent); border-radius:8px; padding:.45rem .95rem; }
.resume .rz-cta:hover { background:var(--accent-deep); }
.resume .rz-reset { font-size:.72rem; font-weight:700; cursor:pointer; color:var(--ink-faint); background:none; border:1px solid var(--rule); border-radius:999px; padding:.2rem .65rem; }
.resume .rz-reset:hover, .resume .rz-reset.armed { color:var(--bad); border-color:var(--bad); }
@media (max-width: 40rem) { .resume .rz-cta { margin-left:0; } }

.phase-progress { display:flex; align-items:center; gap:.7rem; margin:.7rem 0 0; font-family:var(--sans); }
.phase-progress .pp-bar { flex:1 1 auto; height:6px; background:var(--paper-2); border:1px solid var(--rule); border-radius:999px; overflow:hidden; }
.phase-progress .pp-bar span { display:block; height:100%; background:var(--good); transition:width .3s; }
.phase-progress .pp-count { font-size:.72rem; font-weight:700; color:var(--ink-faint); white-space:nowrap; }
.phase-progress.all-done .pp-count { color:var(--good); }

.lesson-card.done { border-left-color:var(--good); }
.lesson-card .done-tick { align-self:center; margin-left:.4rem; font-weight:700; color:var(--good); }

/* ---- Collapsible panels (native <details>) — "try, then reveal" ---------- */
details.panel { border:1px solid var(--rule); border-radius:8px; background:#fff; margin:.5rem 0; overflow:hidden; box-shadow: var(--shadow); }
details.panel + details.panel { margin-top:.45rem; }
details.panel > summary { cursor:pointer; font-family:var(--sans); font-weight:600; font-size:.92rem; color:var(--accent-deep); padding:.7rem .9rem; list-style:none; display:flex; align-items:center; gap:.55rem; }
details.panel > summary::-webkit-details-marker { display:none; }
details.panel > summary::before { content:"▸"; color:var(--accent); transition:transform .15s; display:inline-block; }
details.panel[open] > summary::before { transform:rotate(90deg); }
details.panel[open] > summary { border-bottom:1px solid var(--rule); background:var(--paper-2); }
details.panel .panel-body { padding:.8rem .9rem; font-family:var(--sans); font-size:.88rem; color:var(--ink-soft); line-height:1.5; }
details.panel .panel-body p:last-child { margin-bottom:0; }
details.panel .panel-body pre { font-family: var(--mono); }

/* ---- Step list (numbered build steps) ----------------------------------- */
.steps { list-style:none; counter-reset:step; padding:0; margin:1.6rem 0; display:grid; gap:.9rem; }
.steps > li { position:relative; counter-increment:step; padding:.9rem 1rem .95rem 3.2rem; background:#fff; border:1px solid var(--rule); border-radius:var(--radius); box-shadow:var(--shadow); }
.steps > li::before { content:counter(step); position:absolute; left:.85rem; top:.85rem; width:1.7rem; height:1.7rem; border-radius:999px; background:var(--accent); color:#fff; font-family:var(--sans); font-weight:800; font-size:.92rem; display:flex; align-items:center; justify-content:center; }
.steps .step-title { font-family:var(--sans); font-weight:700; color:var(--accent-deep); margin-bottom:.2rem; }
.steps .step-detail { color:var(--ink-soft); }

/* ---- Recap / takeaways -------------------------------------------------- */
.recap { background: var(--paper-2); border-radius: var(--radius); padding: 1.1rem 1.3rem; margin: 2.4rem 0; }
.recap h3 { margin-top: 0; color: var(--accent-deep); }
.recap ol { margin: 0; }

/* ---- Lesson footer nav -------------------------------------------------- */
.lesson-nav { display: flex; justify-content: space-between; gap: 1rem; border-top: 1px solid var(--rule); margin-top: 3rem; padding-top: 1.4rem; font-family: var(--sans); }
.lesson-nav a { display: block; text-decoration: none; max-width: 47%; }
.lesson-nav .dir { font-size: .7rem; text-transform: uppercase; letter-spacing: .1em; color: var(--ink-faint); font-weight: 700; }
.lesson-nav .ttl { color: var(--accent-deep); font-weight: 600; }
.lesson-nav .next { text-align: right; margin-left: auto; }

.crosslinks { font-family: var(--sans); font-size: .85rem; background: color-mix(in srgb, var(--accent) 7%, #fff); border: 1px solid color-mix(in srgb, var(--accent) 25%, #fff); border-radius: var(--radius); padding: .9rem 1.1rem; margin: 1.8rem 0; }
.crosslinks b { color: var(--accent-deep); }

/* ---- Page footer -------------------------------------------------------- */
.pagefoot { font-family: var(--sans); font-size: .78rem; color: var(--ink-faint); text-align: center; border-top: 1px solid var(--rule); padding: 2rem 0 3rem; margin-top: 3rem; }
.pagefoot a { color: var(--accent-deep); }

/* ===========================================================================
   INDEX / COURSE HOME
   =========================================================================== */
.hero { background: linear-gradient(165deg, var(--dark), var(--accent-deep) 60%, var(--accent)); color: #eeedfb; padding: clamp(2.5rem, 8vw, 5rem) 0 clamp(2rem, 6vw, 3.5rem); }
.hero h1 { font-family: var(--serif); font-weight: 600; font-size: clamp(2.1rem, 1rem + 4vw, 3.6rem); line-height: 1.05; margin: .2rem 0 .6rem; color: #fff; }
.hero p { font-size: 1.18rem; color: rgba(255,255,255,.82); max-width: 40rem; }
.hero strong { color: #ffffff; }
.hero .kicker { color: var(--bright); }
.hero code { background: rgba(255,255,255,.12); color: #e9e8ff; }

.phase { margin: 2.6rem 0; }
.phase-head { display:flex; align-items:baseline; gap:.7rem; flex-wrap:wrap; border-bottom:2px solid var(--rule); padding-bottom:.5rem; }
.phase-head .ph-n { font-family:var(--sans); font-weight:800; font-size:.7rem; letter-spacing:.1em; text-transform:uppercase; color:#fff; background:var(--accent); padding:.2rem .55rem; border-radius:999px; }
.phase-head h2 { margin:0; border:0; }
.phase-head .ph-tag { font-family:var(--sans); font-size:.78rem; color:var(--ink-faint); margin-left:auto; }
.phase-intro { font-family:var(--sans); font-size:.9rem; color:var(--ink-soft); margin:.7rem 0 0; }

.lesson-list { list-style: none; padding: 0; margin: 1rem 0; display: grid; gap: .7rem; }
.lesson-card { display: flex; gap: 1rem; align-items: flex-start; background: #fff; border: 1px solid var(--rule); border-left: 4px solid var(--accent); border-radius: var(--radius); padding: .9rem 1.1rem; text-decoration: none; color: inherit; box-shadow: var(--shadow); transition: transform .08s, border-color .15s; }
.lesson-card:hover { transform: translateX(3px); border-left-color: var(--bright); }
.lesson-card .code { font-family: var(--mono); font-weight: 700; font-size: .9rem; color: var(--accent); min-width: 2.2rem; letter-spacing: .02em; }
.lesson-card .t { font-weight: 600; color: var(--accent-deep); }
.lesson-card .d { font-family: var(--sans); font-size: .84rem; color: var(--ink-soft); margin-top: .15rem; }
.lesson-card.todo { opacity: .6; border-left-color: var(--rule); cursor: default; box-shadow: none; }
.lesson-card.todo .code { color: var(--ink-faint); }
.status-pill { font-family: var(--sans); font-size: .62rem; font-weight: 700; text-transform: uppercase; letter-spacing: .08em; padding: .12rem .45rem; border-radius: 999px; margin-left: auto; align-self: center; white-space: nowrap; }
.status-pill.ready { background: #eef7ef; color: var(--good); border: 1px solid #cfe6d3; }
.status-pill.soon  { background: var(--paper-2); color: var(--ink-faint); border: 1px solid var(--rule); }

.feature { background: linear-gradient(165deg, var(--accent-deep), var(--accent)); color: #eeedfb; border-radius: var(--radius); padding: 1.4rem 1.5rem; margin: 1rem 0; box-shadow: var(--shadow); display: flex; gap: 1.2rem; align-items: center; flex-wrap: wrap; }
.feature .big { font-size: 2rem; }
.feature h3 { margin: 0 0 .25rem; color: #fff; font-family: var(--serif); font-weight: 600; font-size: 1.3rem; }
.feature p { margin: 0; color: rgba(255,255,255,.82); font-family: var(--sans); font-size: .9rem; max-width: 34rem; }
.feature a.cta { margin-left: auto; background: var(--gold); color: #2a1e02; font-family: var(--sans); font-weight: 700; text-decoration: none; padding: .6rem 1.1rem; border-radius: 8px; white-space: nowrap; }
.feature a.cta:hover { background: #d0a02f; }
@media (max-width: 40rem) { .feature a.cta { margin-left: 0; } }

/* ---- Utilities ---------------------------------------------------------- */
.center { text-align: center; }
.muted { color: var(--ink-faint); }
.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 1.2rem; }
@media (max-width: 38rem) { .grid-2 { grid-template-columns: 1fr; } .lesson-nav { flex-direction: column; } .lesson-nav a { max-width: 100%; } }

/* ---- Print — reference pages must print beautifully --------------------- */
@media print {
  :root { --paper: #fff; }
  body { font-size: 11pt; color: #000; }
  .topbar, .lesson-nav, .pagefoot { display: none; }
  .lesson-done, .resume, .phase-progress, .cl-reset, .copy-btn, .calc-foot { display: none; }
  .callout, .sourcebox, .quiz, .frame, .task, .faultfinder, .calc, .steps > li { box-shadow: none; break-inside: avoid; }
  .calc { border: 1px solid #999; }
  .calc-tpl { background: #f4f4f4; color: #000; border: 1px solid #999; }
  a { color: #000; text-decoration: underline; }
  pre { background: #f4f4f4; color: #000; border: 1px solid #999; }
  pre .c { color:#555; } pre .k,pre .s,pre .f,pre .n { color:#000; }
  h2, h3 { break-after: avoid; }
  .compare { grid-template-columns: 1fr 1fr; }
}