/* CB Lab — clean white "engineering drawing" theme.
   Layout: app bar + tab rail on top; each view is a working surface.
   3D views: stage (fluid) + 360px side panel; content views: readable column + instruments. */
:root {
  color-scheme: light;
  --paper: #ffffff;
  --panel: #f6f8f9;
  --panel-2: #eef2f4;
  --line: #e3e8eb;
  --line-strong: #cbd4da;
  --ink: #14212b;
  --ink-2: #4a5b67;
  --ink-3: #7b8a94;
  --accent: #1f6fbf;
  --accent-soft: #e6f0fa;
  --arc: #ef8a17;
  --arc-soft: #fdf1e3;
  --ok: #2f9e5b;
  --warn: #c98f00;
  --bad: #d23b2f;
  --pA: #d1373f;
  --pB: #d99a00;
  --pC: #2463c8;
  --font-display: 'Archivo', 'Arial Narrow', system-ui, sans-serif;
  --font-body: 'IBM Plex Sans', 'Segoe UI', system-ui, sans-serif;
  --font-mono: 'IBM Plex Mono', ui-monospace, 'Cascadia Mono', Consolas, monospace;
  --r: 10px;
  --shadow: 0 1px 2px rgba(20, 33, 43, .06), 0 6px 24px rgba(20, 33, 43, .07);
  --gutter-l: max(16px, env(safe-area-inset-left, 0px));
  --gutter-r: max(16px, env(safe-area-inset-right, 0px));
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html, body { height: 100%; }
body {
  margin: 0; background: var(--paper); color: var(--ink);
  font: 14px/1.5 var(--font-body); -webkit-font-smoothing: antialiased;
}
button, input, select { font: inherit; color: inherit; }
h1, h2, h3, h4 { font-family: var(--font-display); text-wrap: balance; margin: 0; letter-spacing: -0.01em; }
p { margin: 0; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.mono { font-family: var(--font-mono); font-variant-numeric: tabular-nums; }

/* ------------------------------------------------------------------ app bar */
.app { height: 100%; display: flex; flex-direction: column; }
body::before { content: ""; position: fixed; inset: 0 0 auto; height: env(safe-area-inset-top, 0px); z-index: 10; background: var(--paper); }
.appbar {
  position: sticky; top: env(safe-area-inset-top, 0px); z-index: 5; background: var(--paper);
  border-bottom: 1px solid var(--line);
  padding-left: var(--gutter-l); padding-right: var(--gutter-r);
}
.appbar-top { display: flex; align-items: center; gap: 14px; padding-block: 12px 6px; }
.brand { display: flex; align-items: baseline; gap: 12px; min-width: 0; }
.brand-mark {
  font-family: var(--font-display); font-weight: 800; font-size: 22px; letter-spacing: -0.02em;
  font-stretch: 112%; white-space: nowrap;
}
.brand-mark i { font-style: normal; color: var(--accent); }
.brand-sub { color: var(--ink-2); font-size: 13px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.course { margin-left: auto; font: 12px var(--font-mono); color: var(--ink-3); white-space: nowrap; }
.tabs { display: flex; gap: 2px; overflow-x: auto; scrollbar-width: none; margin-inline: -4px; }
.tabs::-webkit-scrollbar { display: none; }
.tab {
  border: 0; background: none; padding: 9px 12px 11px; cursor: pointer; white-space: nowrap;
  color: var(--ink-2); font-weight: 500; border-bottom: 2px solid transparent; font-size: 13.5px;
}
.tab:hover { color: var(--ink); }
.tab[aria-selected="true"] { color: var(--ink); border-bottom-color: var(--ink); }

main { flex: 1; min-height: 0; position: relative; }
.view { height: 100%; overflow: auto; }
.view.fixed { overflow: hidden; }

/* ------------------------------------------------------------------ buttons & inputs */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  border: 1px solid var(--line-strong); background: var(--paper); border-radius: 8px;
  padding: 7px 12px; cursor: pointer; font-weight: 500; font-size: 13px; line-height: 1.2;
}
.btn:hover { border-color: var(--ink-3); }
.btn.primary { background: var(--ink); color: #fff; border-color: var(--ink); }
.btn.primary:hover { background: #24384a; }
.btn.small { padding: 5px 9px; font-size: 12px; }
.btn[aria-pressed="true"] { background: var(--accent-soft); border-color: var(--accent); color: var(--accent); }
.btn:disabled { opacity: .5; cursor: default; }
.seg { display: inline-flex; border: 1px solid var(--line-strong); border-radius: 8px; overflow: hidden; }
.seg button { border: 0; background: var(--paper); padding: 6px 11px; cursor: pointer; font-size: 12.5px; border-right: 1px solid var(--line); }
.seg button:last-child { border-right: 0; }
.seg button[aria-pressed="true"] { background: var(--ink); color: #fff; }
.field { display: grid; gap: 4px; }
.field label, .lbl { font-size: 11.5px; color: var(--ink-3); text-transform: uppercase; letter-spacing: .06em; font-weight: 600; }
.field .row { display: flex; align-items: center; gap: 10px; }
.field output { font: 12.5px var(--font-mono); min-width: 64px; text-align: right; color: var(--ink); }
input[type="range"] { width: 100%; accent-color: var(--ink); }
input[type="search"] {
  width: 100%; border: 1px solid var(--line-strong); border-radius: 8px; padding: 7px 10px; background: var(--paper);
}
.chip {
  display: inline-flex; align-items: center; gap: 4px; padding: 2px 8px; border-radius: 999px;
  font: 11.5px var(--font-mono); background: var(--panel-2); color: var(--ink-2); border: 0; cursor: pointer;
}
.chip:hover { background: var(--accent-soft); color: var(--accent); }
.pill { white-space: nowrap; display: inline-flex; align-items: center; gap: 6px; padding: 3px 9px; border-radius: 999px; font: 600 11.5px var(--font-mono); letter-spacing: .02em; }
.pill.ok { background: #e6f5ec; color: var(--ok); }
.pill.bad { background: #fbe8e6; color: var(--bad); }
.pill.warn { background: #fdf3d9; color: var(--warn); }
.pill.arc { background: var(--arc-soft); color: #b85f00; }
.pill.neutral { background: var(--panel-2); color: var(--ink-2); }

/* ------------------------------------------------------------------ 3D stage */
.stage-layout { height: 100%; display: grid; grid-template-columns: minmax(0, 1fr) 372px; grid-template-rows: minmax(0, 1fr) auto; }
.stage {
  position: relative; min-width: 0; min-height: 0; overflow: hidden;
  background:
    radial-gradient(1200px 600px at 50% 0%, #fbfcfd 0%, #ffffff 60%),
    var(--paper);
}
.stage-canvas { display: block; width: 100%; height: 100%; touch-action: none; }
.side { border-left: 1px solid var(--line); overflow: auto; background: var(--paper); grid-row: 1 / span 2; grid-column: 2; }
.side-inner { padding: 18px 18px 28px; display: grid; gap: 18px; align-content: start; }
.scope { grid-column: 1; border-top: 1px solid var(--line); background: var(--paper); padding: 8px 14px 6px; }
.scope canvas { width: 100%; display: block; cursor: ew-resize; }
.scope .scope-i { height: 150px; }
.scope .scope-t { height: 110px; }
.scope-head { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; font-size: 12px; color: var(--ink-2); }
.scope-head .legend { display: flex; gap: 12px; flex-wrap: wrap; }
.sw { display: inline-block; width: 14px; height: 3px; border-radius: 2px; vertical-align: middle; margin-right: 5px; }

.views-bar { position: absolute; left: 14px; top: 14px; display: flex; flex-direction: column; gap: 6px; z-index: 2; }
.views-bar .btn { background: rgba(255,255,255,.92); backdrop-filter: blur(6px); justify-content: flex-start; }
.status { position: absolute; right: 14px; top: 14px; z-index: 2; display: grid; gap: 6px; justify-items: end; }
.status-card { background: rgba(255,255,255,.94); border: 1px solid var(--line); border-radius: var(--r); padding: 8px 10px; box-shadow: var(--shadow); display: grid; gap: 4px; font-size: 12px; min-width: 196px; }
.status-row { display: flex; justify-content: space-between; gap: 10px; }
.status-row span:first-child { color: var(--ink-3); }
.pos-flag { display: inline-grid; place-items: center; width: 22px; height: 22px; border-radius: 4px; color: #fff; font: 700 13px var(--font-display); }
.pos-flag.closed { background: var(--bad); }
.pos-flag.open { background: var(--ok); }

.toolbar {
  position: absolute; left: 50%; bottom: 14px; transform: translateX(-50%); z-index: 3;
  width: min(820px, calc(100% - 28px));
  background: rgba(255,255,255,.96); border: 1px solid var(--line); border-radius: 14px; box-shadow: var(--shadow);
  padding: 10px 12px; display: grid; gap: 8px;
}
.toolbar-row { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.travel { flex: 1; min-width: 200px; display: grid; gap: 2px; }
.travel-track { position: relative; }
.travel-marks { position: relative; height: 14px; font: 10.5px var(--font-mono); color: var(--ink-3); }
.travel-marks span { position: absolute; transform: translateX(-50%); white-space: nowrap; }
.travel-marks span::before { content: ""; position: absolute; left: 50%; top: -5px; width: 1px; height: 5px; background: var(--ink-3); }
.travel-marks span.r { transform: translateX(calc(-100% + 1px)); }
.travel-marks span.r::before { left: auto; right: 0; }
.travel-marks span.l { transform: none; }
.travel-marks span.l::before { left: 0; }
.toolbar .explode { width: 120px; }
.tb-sep { width: 1px; align-self: stretch; background: var(--line); }

.label-layer { position: absolute; inset: 0; pointer-events: none; z-index: 1; }
.tag {
  position: absolute; left: 0; top: 0; pointer-events: auto; cursor: pointer;
  display: inline-flex; align-items: center; gap: 6px; transform-origin: 0 0;
  border: 1px solid var(--line-strong); background: rgba(255,255,255,.95); border-radius: 999px;
  padding: 2px 9px 2px 4px; font-size: 11.5px; white-space: nowrap; color: var(--ink);
  margin: -11px 0 0 8px; box-shadow: 0 1px 3px rgba(20,33,43,.1);
}
.tag::before { content: ""; position: absolute; left: -9px; top: 50%; width: 8px; height: 1px; background: var(--ink-3); }
.tag::after { content: ""; position: absolute; left: -12px; top: calc(50% - 2.5px); width: 5px; height: 5px; border-radius: 50%; background: var(--ink); }
.tag span { padding-left: 4px; }
.tag.flip::after { left: auto; right: -12px; }
.tag.flip::before { left: auto; right: -9px; }
.tag.flip.shifted::before { right: -10px; }
.tag.shifted::after { top: calc(50% - 2.5px - var(--dy)); }
.tag.shifted::before { left: -10px; top: calc(50% - var(--dy)); width: 1px; height: var(--dy); }
.tag b { display: inline-grid; place-items: center; width: 18px; height: 18px; border-radius: 50%; background: var(--ink); color: #fff; font: 700 11px var(--font-display); }
.tag:hover { border-color: var(--accent); color: var(--accent); }
.hover-tip { position: absolute; z-index: 4; pointer-events: none; background: var(--ink); color: #fff; font-size: 12px; padding: 3px 8px; border-radius: 6px; white-space: nowrap; transform: translate(12px, 12px); }

/* ------------------------------------------------------------------ side panel content */
.card { border: 1px solid var(--line); border-radius: var(--r); padding: 14px; display: grid; gap: 10px; background: var(--paper); }
.card.tint { background: var(--panel); border-color: transparent; }
.eyebrow { font: 600 11px var(--font-mono); letter-spacing: .08em; text-transform: uppercase; color: var(--ink-3); }
.part-title { font-size: 20px; font-weight: 700; line-height: 1.2; }
.part-letter { display: inline-grid; place-items: center; width: 22px; height: 22px; border-radius: 50%; background: var(--ink); color: #fff; font: 700 12px var(--font-display); margin-right: 6px; vertical-align: 2px; }
.muted { color: var(--ink-2); }
.small { font-size: 12.5px; }
ul.ticks { margin: 0; padding-left: 18px; display: grid; gap: 4px; }
ul.ticks li::marker { color: var(--ink-3); }
.kv { display: grid; grid-template-columns: 1fr auto; gap: 6px 14px; font-size: 13px; }
.kv dt { color: var(--ink-2); }
.kv dd { margin: 0; font-family: var(--font-mono); font-variant-numeric: tabular-nums; text-align: right; }
.group-h { display: flex; align-items: baseline; justify-content: space-between; gap: 8px; margin: 4px 0 6px; }
.group-h h3 { font-size: 13px; text-transform: uppercase; letter-spacing: .06em; }
.part-list { display: grid; gap: 1px; }
.part-btn {
  text-align: left; border: 0; background: none; padding: 6px 8px; border-radius: 6px; cursor: pointer;
  display: flex; align-items: center; gap: 8px; font-size: 13px;
}
.part-btn:hover { background: var(--panel); }
.part-btn[aria-current="true"] { background: var(--accent-soft); color: var(--accent); font-weight: 600; }
.part-btn .lt { margin-left: auto; font: 600 11px var(--font-display); color: var(--ink-3); }
.btn-row { display: flex; gap: 8px; flex-wrap: wrap; }
.chips { display: flex; gap: 6px; flex-wrap: wrap; }
.op-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
.op-grid .btn { padding: 10px; font-size: 13.5px; }
.bar { height: 8px; background: var(--panel-2); border-radius: 999px; overflow: hidden; }
.bar i { display: block; height: 100%; background: var(--ink); border-radius: inherit; transition: width .12s linear; }
.bar.green i { background: var(--ok); }
.bar.blue i { background: var(--accent); }
.events { list-style: none; margin: 0; padding: 0; display: grid; gap: 2px; font-size: 12.5px; max-height: 260px; overflow: auto; }
.events li { display: grid; grid-template-columns: 62px 1fr; gap: 8px; padding: 4px 6px; border-radius: 6px; color: var(--ink-3); }
.events li.past { color: var(--ink); }
.events li.now { background: var(--accent-soft); color: var(--ink); }
.events li .mono { color: var(--ink-3); }
.events li.k-clear { font-weight: 600; }
.events li.k-warn { color: var(--warn); }

/* ------------------------------------------------------------------ content views */
.page { padding-left: var(--gutter-l); padding-right: var(--gutter-r); padding-block: 26px 60px; max-width: 1320px; margin: 0 auto; display: grid; gap: 28px; }
.page-head { display: grid; gap: 8px; max-width: 820px; }
.page-head h1 { font-size: clamp(26px, 3.2vw, 36px); font-weight: 800; font-stretch: 108%; line-height: 1.1; }
.page-head p { color: var(--ink-2); font-size: 15px; max-width: 68ch; }
.lect { display: inline-flex; gap: 6px; align-items: center; font: 12px var(--font-mono); color: var(--ink-3); }
.lect b { color: var(--ink); font-weight: 600; }
.split { display: grid; grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr); gap: 28px; align-items: start; }
.split.wide-left { grid-template-columns: minmax(0, 1.3fr) minmax(0, 1fr); }
.stack { display: grid; gap: 16px; align-content: start; min-width: 0; }
.panel { border: 1px solid var(--line); border-radius: var(--r); padding: 16px; display: grid; gap: 12px; min-width: 0; background: var(--paper); }
.panel h2 { font-size: 18px; }
.panel h3 { font-size: 15px; }
.panel.tint { background: var(--panel); border-color: transparent; }
.controls { display: grid; grid-template-columns: repeat(auto-fit, minmax(190px, 1fr)); gap: 14px 18px; }
.chart { width: 100%; height: 280px; display: block; }
.chart.tall { height: 340px; }
.chart.short { height: 200px; }
.figure { border: 1px solid var(--line); border-radius: var(--r); overflow: hidden; background: #fff; }
.figure svg { display: block; width: 100%; height: auto; }
.svg-wrap { overflow-x: auto; }
.readouts { display: grid; grid-template-columns: repeat(auto-fit, minmax(120px, 1fr)); gap: 10px; }
.ro { border-left: 2px solid var(--line-strong); padding: 2px 0 2px 10px; }
.ro .lbl { display: block; }
.ro .val { font: 600 18px var(--font-mono); font-variant-numeric: tabular-nums; }
.ro .val small { font-size: 12px; color: var(--ink-3); font-weight: 400; }
.verdict { display: flex; align-items: center; gap: 10px; font-weight: 600; }
.stages { list-style: none; margin: 0; padding: 0; display: grid; gap: 6px; }
.stage-item { border: 1px solid var(--line); border-radius: 8px; padding: 9px 12px; cursor: pointer; display: grid; grid-template-columns: 26px 1fr; gap: 2px 10px; background: var(--paper); text-align: left; width: 100%; }
.stage-item .n { grid-row: span 2; width: 22px; height: 22px; border-radius: 50%; display: grid; place-items: center; font: 600 11px var(--font-mono); background: var(--panel-2); color: var(--ink-2); }
.stage-item b { font-size: 13.5px; }
.stage-item p { font-size: 12.5px; color: var(--ink-2); display: none; }
.stage-item[aria-current="true"] { border-color: var(--ink); }
.stage-item[aria-current="true"] .n { background: var(--ink); color: #fff; }
.stage-item[aria-current="true"] p { display: block; }
.media { display: grid; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); gap: 14px; }
.media .panel h3 { display: flex; justify-content: space-between; align-items: baseline; gap: 8px; }
.media .range { font: 12px var(--font-mono); color: var(--ink-3); font-weight: 400; }
table.tbl { border-collapse: collapse; width: 100%; font-size: 13px; }
.tbl th, .tbl td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--line); vertical-align: top; }
.tbl th { font-size: 11.5px; text-transform: uppercase; letter-spacing: .06em; color: var(--ink-3); font-weight: 600; }
.tbl td.num { font-family: var(--font-mono); text-align: right; white-space: nowrap; }
.tbl-wrap { overflow-x: auto; }
.callout { border-left: 3px solid var(--accent); background: var(--accent-soft); padding: 10px 14px; border-radius: 0 8px 8px 0; font-size: 13.5px; }
.callout.arc { border-color: var(--arc); background: var(--arc-soft); }
.formula { font: 15px var(--font-mono); background: var(--panel); padding: 10px 14px; border-radius: 8px; overflow-x: auto; white-space: nowrap; }
.subtabs { display: flex; gap: 6px; flex-wrap: wrap; }
.checks { display: grid; gap: 6px; }
.check { display: grid; grid-template-columns: 1fr auto auto; gap: 10px; align-items: center; font-size: 13px; padding: 6px 0; border-bottom: 1px solid var(--line); }
.check .mono { color: var(--ink-2); font-size: 12px; }

/* quiz */
.quiz { max-width: 760px; display: grid; gap: 16px; }
.q-card { border: 1px solid var(--line); border-radius: 14px; padding: 22px; display: grid; gap: 16px; box-shadow: var(--shadow); }
.q-card h2 { font-size: 21px; line-height: 1.3; }
.opts { display: grid; gap: 8px; }
.opt { text-align: left; border: 1px solid var(--line-strong); background: var(--paper); border-radius: 10px; padding: 12px 14px; cursor: pointer; font-size: 14px; display: flex; gap: 12px; align-items: baseline; }
.opt:hover:not(:disabled) { border-color: var(--ink); }
.opt .k { font: 600 12px var(--font-mono); color: var(--ink-3); }
.opt.right { border-color: var(--ok); background: #eef8f2; }
.opt.wrong { border-color: var(--bad); background: #fdf0ee; }
.opt:disabled { cursor: default; }
.progress { height: 4px; background: var(--panel-2); border-radius: 999px; overflow: hidden; }
.progress i { display: block; height: 100%; background: var(--ink); transition: width .25s; }

/* travelling waves */
.nc { text-transform: none; letter-spacing: 0; }
#latFig { overflow-x: auto; }
#latFig svg { min-width: 560px; }
.player { display: flex; align-items: center; gap: 12px; }
.player .btn { min-width: 64px; }
.legend { display: flex; gap: 6px 14px; flex-wrap: wrap; color: var(--ink-2); }
.key { display: inline-flex; align-items: center; gap: 6px; }
.key i { display: inline-block; width: 16px; height: 3px; border-radius: 2px; }
.key.dash i { height: 0; border-top: 2px dashed; background: none; }
.num-in { width: 100%; min-width: 0; border: 1px solid var(--line-strong); border-radius: 6px; padding: 5px 8px; background: var(--paper); font: 12.5px var(--font-mono); }
.num-in:disabled { background: var(--panel); color: var(--ink-3); }
.row-between { display: flex; align-items: center; justify-content: space-between; gap: 10px; flex-wrap: wrap; }
.check-row { display: flex; align-items: center; gap: 8px; font-size: 13px; color: var(--ink-2); }
.sys-edit { display: grid; gap: 12px; border: 1px solid var(--line); border-radius: var(--r); padding: 12px; background: var(--panel); }
.sys-edit .controls { grid-template-columns: repeat(auto-fit, minmax(130px, 1fr)); gap: 10px 12px; }
.tbl.compact th, .tbl.compact td { padding: 5px 6px; }
.tbl.compact td:nth-child(2), .tbl.compact td:nth-child(3) { width: 80px; }
.formula.small-formula { font-size: 13px; }

.foot { color: var(--ink-3); font-size: 12px; max-width: 90ch; }

/* ------------------------------------------------------------------ responsive */
@media (max-width: 1080px) {
  .split, .split.wide-left { grid-template-columns: minmax(0, 1fr); }
}
@media (max-width: 900px) {
  .view.fixed { overflow: auto; }
  .stage-layout { height: auto; grid-template-columns: minmax(0, 1fr); grid-template-rows: auto; }
  .stage { height: 64vh; min-height: 420px; }
  .side { grid-row: auto; grid-column: 1; border-left: 0; border-top: 1px solid var(--line); overflow: visible; }
  .scope { grid-column: 1; }
  .brand-sub { display: none; }
  .views-bar { flex-direction: row; flex-wrap: wrap; right: 120px; }
  .views-bar .btn { padding: 5px 8px; font-size: 11.5px; }
  .status-card { min-width: 0; }
  .toolbar { bottom: 8px; padding: 8px; }
  .toolbar .explode { width: 90px; }
}
@media (max-width: 560px) {
  .status { display: none; }
  .views-bar { right: 14px; }
  .course { display: none; }
}
@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; }
}