:root {
  --bg: #f6f6f3; --panel: #ffffff; --text: #1f2328; --muted: #646a72; --line: #dcdfd8;
  --accent: #2f6fde; --accent-soft: #e6eefc; --ok: #19804a; --ok-soft: #e3f4ea; --bad: #b9460f; --bad-soft: #fdeee4;
  --x: #d9480f; --y: #2b8a3e; --z: #1c64d6; --edge: #30343a; --hidden: #9aa0a6; --sel: #e8590c; --scene: #fbfbf9;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #141619; --panel: #1d2024; --text: #e7e9ec; --muted: #9ba1a8; --line: #33373d;
    --accent: #79a6ff; --accent-soft: #1f2b44; --ok: #4cc38a; --ok-soft: #173326; --bad: #ff9a5c; --bad-soft: #3a2316;
    --x: #ff8047; --y: #63d47f; --z: #6aa5ff; --edge: #d3d7dc; --hidden: #6e747b; --sel: #ffb066; --scene: #181a1d;
  }
}
:root[data-theme="dark"] {
  --bg: #141619; --panel: #1d2024; --text: #e7e9ec; --muted: #9ba1a8; --line: #33373d;
  --accent: #79a6ff; --accent-soft: #1f2b44; --ok: #4cc38a; --ok-soft: #173326; --bad: #ff9a5c; --bad-soft: #3a2316;
  --x: #ff8047; --y: #63d47f; --z: #6aa5ff; --edge: #d3d7dc; --hidden: #6e747b; --sel: #ffb066; --scene: #181a1d;
}
* { box-sizing: border-box; }
html, body { margin: 0; }
body {
  background: var(--bg); color: var(--text);
  font-family: -apple-system, "PingFang SC", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
  font-size: 16px; line-height: 1.65;
}

:where(.lesson) header {
  display: flex; align-items: center; gap: 12px; flex-wrap: wrap;
  padding: 10px 16px; border-bottom: 1px solid var(--line); background: var(--panel);
}
:where(.lesson) header h1 { font-size: 17px; margin: 0; font-weight: 600; }
:where(.lesson) .steps { display: flex; gap: 6px; flex-wrap: wrap; margin-left: auto; }
:where(.lesson) .steps[hidden] { display: none; }
:where(.lesson) .steps button {
  border: 1px solid var(--line); background: transparent; color: var(--muted);
  border-radius: 999px; padding: 3px 12px; font-size: 14px; cursor: pointer;
}
:where(.lesson) .steps button.on { background: var(--accent); border-color: var(--accent); color: #fff; }
:where(.lesson) .steps button:disabled { opacity: .45; cursor: default; }
:where(.lesson) .steps button.done { color: var(--ok); border-color: var(--ok); }
:where(.lesson) .layout { display: grid; grid-template-columns: minmax(0, 1.35fr) minmax(0, 1fr); height: calc(100vh - var(--header-height, 53px)); }
:where(.lesson) .stage { position: relative; background: var(--scene); border-right: 1px solid var(--line); overflow: hidden; }
:where(.lesson) #gl, :where(.lesson) #labels, :where(.lesson) #paper { position: absolute; inset: 0; }
:where(.lesson) #gl { display: block; width: 100%; height: 100%; }
:where(.lesson) #labels { pointer-events: none; }
:where(.lesson) #paper { display: none; background: var(--scene); }
:where(.lesson) .stage.paper #paper { display: block; }
:where(.lesson) .stage.paper #gl, :where(.lesson) .stage.paper #labels { visibility: hidden; }
:where(.lesson) .tools { position: absolute; top: 10px; left: 10px; display: flex; gap: 6px; z-index: 5; flex-wrap: wrap; }
:where(.lesson) .tools button {
  font-size: 13px; padding: 4px 10px; border-radius: 6px; cursor: pointer;
  border: 1px solid var(--line); background: var(--panel); color: var(--text);
}
:where(.lesson) .tools button.on { border-color: var(--accent); color: var(--accent); }
:where(.lesson) .stage-tip {
  position: absolute; bottom: 10px; left: 10px; right: 10px; z-index: 5; pointer-events: none;
  font-size: 13px; color: var(--muted); text-align: center;
}
:where(.lesson) .panel { overflow-y: auto; padding: 18px 20px 40px; background: var(--panel); }
:where(.lesson) .panel h2 { font-size: 20px; margin: 0 0 10px; }
:where(.lesson) .panel p { margin: 8px 0; }
:where(.lesson) .muted { color: var(--muted); font-size: 14px; }
:where(.lesson) .card { border: 1px solid var(--line); border-radius: 10px; padding: 12px 14px; margin: 12px 0; }
:where(.lesson) .card.key { border-color: var(--accent); background: var(--accent-soft); }
:where(.lesson) .coord { font-size: 26px; font-weight: 600; letter-spacing: 1px; margin: 4px 0; }
:where(.lesson) .cx { color: var(--x); }
:where(.lesson) .cy { color: var(--y); }
:where(.lesson) .cz { color: var(--z); }
:where(.lesson) ol.walk { padding-left: 20px; margin: 6px 0; }
:where(.lesson) ol.walk li { margin: 4px 0; }
:where(.lesson) .inputs { display: flex; align-items: center; gap: 4px; font-size: 22px; flex-wrap: wrap; margin: 8px 0; }
:where(.lesson) .inputs input {
  width: 64px; font-size: 20px; padding: 4px 6px; text-align: center; border-radius: 6px;
  border: 2px solid var(--line); background: var(--bg); color: var(--text);
}
:where(.lesson) .inputs input.ix { border-color: var(--x); }
:where(.lesson) .inputs input.iy { border-color: var(--y); }
:where(.lesson) .inputs input.iz { border-color: var(--z); }
:where(.lesson) .inputs input.wrong { background: var(--bad-soft); }
:where(.lesson) .inputs input.right { background: var(--ok-soft); }
:where(.lesson) .row { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 8px; }
:where(.lesson) .btn {
  font-size: 15px; padding: 7px 16px; border-radius: 8px; cursor: pointer;
  border: 1px solid var(--accent); background: var(--accent); color: #fff;
}
:where(.lesson) .btn.ghost { background: transparent; color: var(--accent); }
:where(.lesson) .btn:disabled { opacity: .45; cursor: default; }
:where(.lesson) .fb { margin-top: 10px; padding: 8px 12px; border-radius: 8px; font-size: 15px; display: none; }
:where(.lesson) .fb.ok { display: block; background: var(--ok-soft); color: var(--ok); }
:where(.lesson) .fb.bad { display: block; background: var(--bad-soft); color: var(--bad); }
:where(.lesson) .chips { display: flex; gap: 6px; flex-wrap: wrap; margin: 6px 0; }
:where(.lesson) .chips span { font-size: 13px; padding: 2px 10px; border-radius: 999px; border: 1px solid var(--line); color: var(--muted); }
:where(.lesson) .chips span.got { color: var(--ok); border-color: var(--ok); }
:where(.lesson) textarea {
  width: 100%; min-height: 72px; font: inherit; font-size: 15px; padding: 8px; border-radius: 8px;
  border: 1px solid var(--line); background: var(--bg); color: var(--text);
}
:where(.lesson) .rate button { font-size: 14px; padding: 5px 12px; border-radius: 999px; border: 1px solid var(--line); background: transparent; color: var(--text); cursor: pointer; }
:where(.lesson) .rate button.on { border-color: var(--accent); color: var(--accent); background: var(--accent-soft); }
:where(.lesson) .lbl { font-size: 15px; font-weight: 600; color: var(--edge); text-shadow: 0 0 3px var(--scene), 0 0 3px var(--scene); white-space: nowrap; }
:where(.lesson) .lbl.sel { color: var(--sel); font-size: 16px; }
:where(.lesson) .lbl.axis { font-style: italic; font-size: 16px; }
:where(.lesson) .lbl.tick { font-size: 11px; font-weight: 400; color: var(--muted); }
:where(.lesson) .lbl.val { font-size: 14px; padding: 0 4px; border-radius: 4px; background: var(--panel); }
:where(.lesson) pre.log { white-space: pre-wrap; overflow-wrap: anywhere; font-size: 13px; background: var(--bg); padding: 10px; border-radius: 8px; border: 1px solid var(--line); }
@media (max-width: 860px) {
:where(.lesson) .layout { grid-template-columns: 1fr; height: auto; }
:where(.lesson) .stage { height: 56vh; border-right: 0; border-bottom: 1px solid var(--line); }
:where(.lesson) .panel { overflow: visible; padding: 16px; }
:where(.lesson) .steps { margin-left: 0; }
}
:where(.lesson) .panel, :where(.lesson) .card, :where(.lesson) .fb { min-width: 0; }

:where(.exact-inputs) .inputs input.scalar { width: 150px; }
:where(.exact-inputs) .formula { min-width: 0; }
:where(.exact-inputs) .input-preview { max-width: 100%; overflow-x: auto; padding: .25em 0; }
:where(.exact-inputs) [hidden] { display: none !important; }
:where(.exact-inputs) .tabs button.on, :where(.exact-inputs) .vertex-buttons button.on { background: var(--accent-soft); }
:where(.exact-inputs) button:focus-visible, :where(.exact-inputs) input:focus-visible, :where(.exact-inputs) textarea:focus-visible { outline: 3px solid var(--accent); outline-offset: 3px; }
:where(.exact-inputs) #paper { width: 100%; height: 100%; }



.katex { color: inherit; }
.katex-display { max-width: 100%; overflow-x: auto; overflow-y: hidden; padding: .25em 0; }
.katex-display > .katex { text-align: left; }

.term {
  display: inline; padding: 0 1px; border: 0; border-bottom: 1px dashed currentColor;
  border-radius: 0; background: transparent; color: var(--accent); font: inherit; cursor: pointer;
}
.term:focus-visible, .glossary-card :focus-visible { outline: 3px solid var(--accent); outline-offset: 3px; }
.glossary-card {
  position: fixed; inset: auto; margin: 0; width: min(380px, calc(100vw - 24px));
  max-width: none; max-height: calc(100dvh - 24px); overflow-y: auto;
  padding: 18px; border: 1px solid var(--line); border-radius: 12px;
  background: var(--panel); color: var(--text); box-shadow: 0 8px 30px #0003;
  font: inherit; overflow-wrap: anywhere;
}
.glossary-card::backdrop { background: rgb(0 0 0 / .12); }
.glossary-card h2 { margin: 0 0 8px; font-size: 20px; }
.glossary-card h3 { margin: 12px 0 4px; font-size: 15px; }
.glossary-card p { margin: 8px 0; }
.glossary-card svg { display: block; width: 100%; max-height: 170px; color: var(--accent); }
.glossary-card a { color: var(--accent); }
.glossary-note { color: var(--muted); font-size: 14px; }
.glossary-close {
  min-height: 44px; padding: 7px 18px; margin-top: 8px; border: 0; border-radius: 8px;
  background: var(--accent); color: var(--panel); font: inherit; cursor: pointer;
}
@media (max-width: 860px) {
  .glossary-card {
    inset: auto 0 0; width: 100%; max-height: 80dvh; border-radius: 16px 16px 0 0;
    padding-bottom: max(18px, env(safe-area-inset-bottom));
  }
  .glossary-card::backdrop { background: rgb(0 0 0 / .3); }
  .glossary-close { width: 100%; }
}

@media print {
  body:where(.diagnosis) { background: #fff; color: #000; font-size: 11pt; }
  :where(.diagnosis) header { display: block; background: #fff; padding: 0 0 4mm; }
  :where(.diagnosis) main { max-width: none; padding: 5mm 0 0; }
  :where(.diagnosis) .katex-display { overflow: visible; }
}

.plane2d { display: block; width: 100%; height: 100%; }
.plane2d text { paint-order: stroke; stroke: var(--scene); stroke-width: 4px; stroke-linejoin: round; }
.plane2d [data-point]:focus-visible circle { stroke: var(--accent); stroke-width: 3px; }
:where(.lesson) .stage.assessment-stage { display: none; }
:where(.lesson) .layout.assessment-layout { grid-template-columns: minmax(0, 760px); justify-content: center; }
:where(.lesson) .slope-profile { width: 100%; height: auto; color: var(--accent); }
:where(.lesson) .slope-profile text { fill: var(--text); font-size: 13px; }