:root {
  color-scheme: light;
  --cream: #f4f6f8;
  --paper: #ffffff;
  --paper-strong: #ffffff;
  --ink: #10243b;
  --muted: #607086;
  --line: #d9e1e9;
  --line-strong: #bcc9d6;
  --oxford-950: #00152f;
  --oxford-900: #002147;
  --oxford-800: #073361;
  --oxford-700: #164c7c;
  --teal: #0b5f91;
  --teal-dark: #003a68;
  --teal-soft: #e5f0f7;
  --sky: #d9edf7;
  --coral: #e56352;
  --coral-soft: #fce9e5;
  --gold: #f1b434;
  --gold-soft: #fff4d6;
  --blue: #377bb8;
  --danger: #a93635;
  --success: #56b28b;
  --shadow-sm: 0 1px 2px rgba(0, 33, 71, .04), 0 8px 24px rgba(0, 33, 71, .06);
  --shadow-lg: 0 24px 70px rgba(0, 33, 71, .11);
  --radius-xl: 24px;
  --radius-lg: 20px;
  --radius-md: 13px;
  --font-sans: Inter, ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-serif: Iowan Old Style, "Palatino Linotype", "Book Antiqua", Palatino, Georgia, serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 112px; }
body {
  margin: 0;
  min-width: 320px;
  min-height: 100vh;
  background:
    radial-gradient(circle at 8% 2%, rgba(76, 151, 197, .11), transparent 24rem),
    radial-gradient(circle at 94% 30%, rgba(241, 180, 52, .09), transparent 27rem),
    var(--cream);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

button, input, select, textarea { color: inherit; font: inherit; }
button, select, summary { cursor: pointer; }
button { -webkit-tap-highlight-color: transparent; }
button:focus-visible,
input:focus-visible,
select:focus-visible,
textarea:focus-visible,
summary:focus-visible {
  outline: 3px solid var(--oxford-700);
  outline-offset: 3px;
}
.topbar button:focus-visible,
.topbar a:focus-visible,
.operation-panel button:focus-visible,
.operation-panel select:focus-visible,
.insight-panel button:focus-visible,
.insight-panel input:focus-visible,
.insight-panel summary:focus-visible { outline-color: var(--gold); }
button:disabled { cursor: not-allowed; opacity: .48; }
[hidden] { display: none !important; }
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  left: 1.25rem;
  top: -6rem;
  z-index: 100;
  padding: .78rem 1rem;
  border-radius: 0 0 11px 11px;
  background: var(--gold);
  color: var(--oxford-950);
  font-size: .82rem;
  font-weight: 800;
}
.skip-link:focus { top: 0; }

.page-shell { width: min(100%, 1540px); margin: 0 auto; padding: 0 28px; }

/* Navigation */
.topbar {
  position: sticky;
  top: 12px;
  z-index: 40;
  min-height: 76px;
  margin-top: 12px;
  padding: 10px 14px 10px 18px;
  display: grid;
  grid-template-columns: minmax(185px, 1fr) auto minmax(185px, 1fr);
  align-items: center;
  gap: 18px;
  border: 1px solid rgba(255, 255, 255, .12);
  border-radius: 19px;
  background: rgba(0, 33, 71, .97);
  box-shadow: 0 14px 40px rgba(0, 25, 55, .2);
}
@supports (backdrop-filter: blur(16px)) {
  .topbar { background: rgba(0, 33, 71, .94); backdrop-filter: blur(16px); }
}

.brand {
  width: max-content;
  display: inline-flex;
  align-items: center;
  gap: 11px;
  color: white;
  text-decoration: none;
}
.brand-copy { display: flex; flex-direction: column; line-height: 1.08; }
.brand-copy strong { font-size: .88rem; letter-spacing: -.018em; white-space: nowrap; }
.brand-copy small {
  margin-top: 4px;
  color: #a9c0d4;
  font-size: .57rem;
  font-weight: 780;
  letter-spacing: .13em;
  text-transform: uppercase;
}
.brand-mark {
  position: relative;
  width: 40px;
  height: 40px;
  flex: 0 0 auto;
  overflow: hidden;
  border: 1px solid rgba(255, 255, 255, .18);
  border-radius: 11px;
  background: rgba(255, 255, 255, .08);
}
.brand-mark::after {
  content: "";
  position: absolute;
  left: 8px;
  bottom: 8px;
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: white;
  transform: translate(-50%, 50%);
}
.basis-axis {
  position: absolute;
  left: 8px;
  bottom: 8px;
  height: 2px;
  border-radius: 99px;
  transform-origin: left center;
}
.basis-axis::after {
  content: "";
  position: absolute;
  top: 50%;
  right: -1px;
  width: 6px;
  height: 6px;
  border-top: 2px solid currentColor;
  border-right: 2px solid currentColor;
  transform: translateY(-50%) rotate(45deg);
}
.basis-reference-x, .basis-reference-y { width: 24px; background: #8eaac3; color: #8eaac3; opacity: .45; }
.basis-reference-x { transform: rotate(0deg); }
.basis-reference-y { transform: rotate(-90deg); }
.basis-transformed-x { width: 25px; background: var(--gold); color: var(--gold); transform: rotate(-38deg); }
.basis-transformed-y { width: 23px; background: #8fd0ee; color: #8fd0ee; transform: rotate(-76deg); }

.workspace-nav {
  max-width: 100%;
  display: flex;
  align-items: center;
  gap: 3px;
  padding: 4px;
  border: 1px solid rgba(255, 255, 255, .12);
  border-radius: 14px;
  background: rgba(255, 255, 255, .07);
}
.nav-tab {
  min-height: 44px;
  padding: 0 15px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  border: 0;
  border-radius: 10px;
  background: transparent;
  color: #c1d0df;
  font-size: .82rem;
  font-weight: 720;
  transition: color .18s ease, background .18s ease, transform .18s ease;
}
.nav-tab .tab-icon {
  width: 23px;
  height: 23px;
  display: grid;
  place-items: center;
  border-radius: 7px;
  background: rgba(255, 255, 255, .08);
  font-size: .9rem;
}
.nav-tab:hover { color: white; background: rgba(255, 255, 255, .08); }
.nav-tab.is-active {
  background: white;
  color: var(--oxford-900);
  box-shadow: 0 5px 16px rgba(0, 0, 0, .18);
}
.nav-tab.is-active .tab-icon { background: var(--teal-soft); color: var(--teal-dark); }
.save-status { justify-self: end; color: #bfd0df; font-size: .7rem; white-space: nowrap; }
.save-status span { margin-right: 6px; color: #71d0a8; font-size: .55rem; }

/* Page hierarchy */
main { padding: 52px 0 68px; }
.workspace-panel { animation: panel-in .32s ease both; }
@keyframes panel-in { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: none; } }
.workspace-heading {
  margin: 0 0 34px;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  align-items: end;
}
.workspace-heading.compact { margin-bottom: 30px; }
.eyebrow, .kicker {
  margin: 0 0 9px;
  color: var(--teal);
  font-size: .67rem;
  font-weight: 850;
  text-transform: uppercase;
  letter-spacing: .145em;
}
.eyebrow { display: flex; align-items: center; gap: 9px; }
.eyebrow > span {
  width: 26px;
  height: 26px;
  display: grid;
  place-items: center;
  border: 1px solid #b8ccdc;
  border-radius: 8px;
  background: rgba(255, 255, 255, .72);
  color: var(--oxford-700);
  font-size: .61rem;
  letter-spacing: 0;
  box-shadow: var(--shadow-sm);
}
h1, h2, h3, p { margin-top: 0; }
h1 {
  max-width: 840px;
  margin-bottom: 0;
  color: var(--oxford-950);
  font-size: clamp(2.6rem, 4.3vw, 4.35rem);
  line-height: .98;
  letter-spacing: -.058em;
  font-weight: 720;
}
h1 em { color: var(--oxford-700); font-family: var(--font-serif); font-weight: 500; }
h2 { margin-bottom: 0; color: var(--oxford-950); font-size: 1.15rem; letter-spacing: -.026em; }
h3 { margin: 0; color: var(--oxford-950); font-size: .79rem; letter-spacing: -.01em; }
.surface {
  border: 1px solid rgba(0, 33, 71, .1);
  border-radius: var(--radius-xl);
  background: rgba(255, 255, 255, .96);
  box-shadow: var(--shadow-sm);
}

/* Calculator */
.calculator-layout {
  display: grid;
  grid-template-columns: minmax(210px, .72fr) minmax(390px, 1.35fr) minmax(310px, .92fr);
  gap: 17px;
  align-items: stretch;
}
.library-panel, .editor-panel, .operation-panel { min-height: 486px; padding: 23px; }
.library-panel { background: linear-gradient(155deg, #f8fbfd 0%, #fff 52%); }
.panel-heading, .result-heading, .subheading-row, .visual-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}
.panel-heading { min-height: 49px; }
.icon-button {
  width: 40px;
  height: 40px;
  border: 1px solid #bfd0de;
  border-radius: 12px;
  background: white;
  color: var(--oxford-700);
  font-size: 1.35rem;
  line-height: 1;
  box-shadow: 0 5px 15px rgba(0, 33, 71, .07);
  transition: .18s ease;
}
.icon-button:hover { border-color: #91b3cb; background: var(--teal-soft); transform: translateY(-1px); }

.matrix-library {
  max-height: 270px;
  margin-top: 19px;
  padding-right: 3px;
  display: grid;
  gap: 7px;
  overflow-y: auto;
  scrollbar-color: #b8c8d4 transparent;
}
.matrix-library-item {
  width: 100%;
  min-height: 62px;
  padding: 10px 11px 10px 13px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  border: 1px solid transparent;
  border-radius: 13px;
  background: transparent;
  color: var(--ink);
  text-align: left;
  transition: .16s ease;
}
.matrix-library-item:hover { border-color: #d1dde7; background: white; box-shadow: 0 5px 15px rgba(0, 33, 71, .05); }
.matrix-library-item.is-active {
  border-color: #a9c7da;
  background: var(--teal-soft);
  color: var(--oxford-900);
}
.matrix-library-item strong { display: block; font-size: .84rem; }
.matrix-library-item small { color: var(--muted); font-size: .66rem; }
.matrix-library-preview { display: flex; align-items: center; gap: 8px; }
.selected-indicator {
  padding: 3px 6px;
  border-radius: 999px;
  background: var(--oxford-900);
  color: white;
  font-size: .52rem;
  font-weight: 800;
  letter-spacing: .035em;
  text-transform: uppercase;
}
.mini-matrix {
  position: relative;
  padding: 3px 7px;
  display: grid;
  grid-template-columns: repeat(var(--columns), 5px);
  gap: 2px;
}
.mini-matrix::before, .mini-matrix::after {
  content: "";
  position: absolute;
  inset-block: 0;
  width: 3px;
  border: 1px solid currentColor;
  opacity: .58;
}
.mini-matrix::before { left: 0; border-right: 0; }
.mini-matrix::after { right: 0; border-left: 0; }
.mini-matrix i { width: 5px; height: 5px; display: block; border-radius: 1px; background: currentColor; opacity: .38; }

.history-block { margin-top: 22px; padding-top: 18px; border-top: 1px solid var(--line); }
.text-button {
  min-height: 32px;
  padding: 5px 7px;
  border: 0;
  border-radius: 8px;
  background: transparent;
  color: var(--teal-dark);
  font-size: .72rem;
  font-weight: 760;
}
.text-button:hover { background: var(--teal-soft); text-decoration: none; }
.text-button.destructive { color: var(--danger); }
.text-button.destructive:hover { background: var(--coral-soft); }
.history-list { margin: 10px 0 0; padding: 0; display: grid; gap: 3px; list-style: none; }
.history-list li { color: var(--muted); font-size: .69rem; line-height: 1.35; }
.history-list button {
  width: 100%;
  padding: 8px 5px;
  display: flex;
  justify-content: space-between;
  gap: 8px;
  border: 0;
  border-radius: 8px;
  background: transparent;
  color: inherit;
  text-align: left;
}
.history-list button:hover { background: #f2f6f9; color: var(--oxford-900); }
.history-list .empty-history { padding: 9px 4px; }

.editor-heading { align-items: flex-start; }
.dimension-controls { display: flex; align-items: end; gap: 7px; color: var(--muted); }
.dimension-controls label { display: grid; gap: 3px; font-size: .7rem; font-weight: 750; text-transform: uppercase; letter-spacing: .07em; }
select, input, textarea {
  border: 1px solid var(--line-strong);
  border-radius: 11px;
  background: white;
  transition: border-color .16s ease, box-shadow .16s ease, background .16s ease;
}
select:hover, input:hover, textarea:hover { border-color: #92a9bd; }
select:focus, input:focus, textarea:focus { border-color: var(--oxford-700); box-shadow: 0 0 0 3px rgba(22, 76, 124, .1); }
select { min-height: 39px; padding: 0 31px 0 11px; }
.dimension-controls select { min-width: 58px; min-height: 34px; padding: 0 7px; }
.matrix-editor-wrap {
  min-height: 285px;
  margin: 18px -2px 0;
  padding: 30px 18px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid #e0e8ee;
  border-radius: 18px;
  background:
    linear-gradient(rgba(0, 33, 71, .025) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0, 33, 71, .025) 1px, transparent 1px),
    #f8fafc;
  background-size: 24px 24px;
  overflow: auto;
}
.matrix-editor { display: grid; grid-template-columns: repeat(var(--columns), minmax(54px, 68px)); gap: 8px; }
.matrix-cell {
  width: 100%;
  height: 48px;
  border-color: #cad5df;
  border-radius: 10px;
  background: rgba(255, 255, 255, .97);
  color: var(--oxford-950);
  font-size: .95rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  text-align: center;
  box-shadow: 0 3px 10px rgba(0, 33, 71, .045);
}
.matrix-cell:focus { background: white; box-shadow: 0 0 0 3px rgba(55, 123, 184, .12), 0 5px 14px rgba(0, 33, 71, .08); }
.matrix-cell[aria-invalid="true"] { border-color: var(--danger); background: #fff7f5; }
.matrix-bracket {
  width: 13px;
  min-width: 13px;
  max-height: 246px;
  margin: auto 6px;
  align-self: stretch;
  border: 3px solid var(--oxford-700);
  opacity: .8;
}
.matrix-bracket.left { border-right: 0; border-radius: 9px 0 0 9px; }
.matrix-bracket.right { border-left: 0; border-radius: 0 9px 9px 0; }
.editor-actions {
  margin-top: 16px;
  padding-top: 14px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  border-top: 1px solid var(--line);
}
.editor-actions p { margin: 0; color: var(--muted); font-size: .68rem; }
.editor-actions code { padding: 2px 5px; border-radius: 5px; background: #eef3f7; color: var(--oxford-900); }
.editor-actions > div { display: flex; flex-wrap: wrap; justify-content: flex-end; gap: 1px; }
.inline-paste { margin-top: 16px; padding-top: 16px; border-top: 1px solid var(--line); }
.inline-paste label { display: block; margin-bottom: 7px; color: var(--muted); font-size: .72rem; font-weight: 700; }
.inline-paste textarea { width: 100%; padding: 11px 12px; resize: vertical; }
.inline-paste > div { margin-top: 9px; display: flex; justify-content: flex-end; gap: 8px; }

.operation-panel {
  border-color: rgba(255, 255, 255, .08);
  background: linear-gradient(150deg, var(--oxford-900), var(--oxford-950));
  color: white;
  box-shadow: var(--shadow-lg);
}
.operation-panel h2 { color: white; }
.operation-panel .kicker { color: #92cbe8; }
.operation-picker { margin-top: 23px; display: flex; flex-wrap: wrap; gap: 7px; }
.operation-chip, .preset-button {
  min-height: 36px;
  padding: 7px 11px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: white;
  color: var(--muted);
  font-size: .7rem;
  font-weight: 760;
}
.operation-chip {
  border-color: rgba(255, 255, 255, .18);
  background: rgba(255, 255, 255, .07);
  color: #c2d1e0;
}
.operation-chip:hover { border-color: rgba(255, 255, 255, .34); background: rgba(255, 255, 255, .12); color: white; }
.operation-chip.is-active { border-color: white; background: white; color: var(--oxford-900); box-shadow: 0 5px 15px rgba(0, 0, 0, .18); }
.operand-row { margin-top: 22px; display: grid; grid-template-columns: 1fr; gap: 9px; }
.operand-row.has-second { grid-template-columns: 1fr 1fr; }
.selected-operand {
  min-height: 62px;
  padding: 10px 12px;
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-content: center;
  gap: 1px 10px;
  border: 1px solid rgba(255, 255, 255, .18);
  border-radius: 11px;
  background: rgba(255, 255, 255, .08);
}
.selected-operand span { grid-column: 1 / -1; color: #9fb5c9; font-size: .58rem; font-weight: 750; text-transform: uppercase; letter-spacing: .075em; }
.selected-operand strong { overflow: hidden; color: white; font-size: .82rem; text-overflow: ellipsis; white-space: nowrap; }
.selected-operand small { align-self: center; color: #b9c9d8; font-size: .63rem; font-variant-numeric: tabular-nums; }
.operand-row label, .visual-toolbar label, .vector-panel label, dialog label {
  display: grid;
  gap: 6px;
  color: var(--muted);
  font-size: .68rem;
  font-weight: 750;
}
.operation-panel .operand-row label { color: #b9c9d8; }
.operand-row select { width: 100%; }
.operation-panel select { border-color: rgba(255, 255, 255, .2); background: rgba(255, 255, 255, .1); color: white; }
.operation-panel select option { color: var(--ink); background: white; }
.operation-summary {
  min-height: 78px;
  margin-top: 18px;
  padding: 15px 16px;
  border: 1px solid rgba(241, 180, 52, .28);
  border-left: 3px solid var(--gold);
  border-radius: 12px;
  background: rgba(241, 180, 52, .1);
  color: #f5dfaa;
  font-size: .82rem;
  line-height: 1.55;
}
.button {
  min-height: 44px;
  padding: 0 17px;
  border: 1px solid transparent;
  border-radius: 11px;
  font-size: .78rem;
  font-weight: 800;
  transition: background .16s ease, border-color .16s ease, transform .16s ease, box-shadow .16s ease;
}
.button.primary { background: var(--oxford-900); color: white; box-shadow: 0 8px 18px rgba(0, 33, 71, .16); }
.button.primary:hover { background: var(--oxford-800); transform: translateY(-1px); }
.button.secondary { border-color: var(--line-strong); background: white; color: var(--oxford-900); }
.button.secondary:hover { border-color: #9ab2c5; background: var(--teal-soft); }
.operation-panel .calculate-button { background: var(--gold); color: var(--oxford-950); box-shadow: 0 10px 24px rgba(0, 0, 0, .2); }
.operation-panel .calculate-button:hover { background: #ffc552; }
.calculate-button { width: 100%; margin-top: 17px; display: flex; align-items: center; justify-content: space-between; }
.calculate-button span { font-size: 1.15rem; }
.form-error { min-height: 18px; margin: 9px 0 0; color: var(--danger); font-size: .7rem; line-height: 1.45; }
.editor-error:empty { min-height: 0; margin-top: 0; }
.operation-panel .form-error { color: #ffaea3; }
.operation-panel .form-error[data-visible="true"] {
  margin-top: 13px;
  padding: 12px 13px;
  display: grid;
  gap: 4px;
  border: 1px solid rgba(255, 174, 163, .32);
  border-radius: 11px;
  background: rgba(169, 54, 53, .16);
  color: #ffe1dc;
}
.operation-panel .form-error strong { color: white; font-size: .75rem; }
.operation-panel .form-error span,
.operation-panel .form-error small { display: block; }
.operation-panel .form-error small { color: #ffc5bb; font-size: .67rem; }

/* Results and teaching */
.result-section {
  position: relative;
  min-height: 246px;
  margin-top: 17px;
  padding: 25px 27px 27px;
  overflow: hidden;
}
.result-section::before {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: 4px;
  background: linear-gradient(var(--gold), var(--teal));
}
.result-heading { align-items: flex-start; }
.result-format-controls { display: flex; align-items: center; gap: 9px; }
.segmented { display: flex; padding: 3px; border: 1px solid #d7e0e8; border-radius: 10px; background: #edf2f6; }
.segmented button {
  min-height: 32px;
  padding: 0 12px;
  border: 0;
  border-radius: 7px;
  background: transparent;
  color: var(--muted);
  font-size: .68rem;
  font-weight: 780;
}
.segmented button.is-active { background: white; color: var(--oxford-900); box-shadow: 0 2px 8px rgba(0, 33, 71, .1); }
.precision-control { display: flex; align-items: center; gap: 6px; color: var(--muted); font-size: .63rem; font-weight: 750; }
.precision-control select { min-height: 38px; padding: 0 7px; }
.result-empty {
  min-height: 148px;
  margin-top: 18px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 8px;
  border: 1px dashed #cbd8e2;
  border-radius: 16px;
  background:
    radial-gradient(circle at center, rgba(217, 237, 247, .65), transparent 58%),
    #fafcfd;
  color: var(--muted);
}
.result-empty p { margin: 0; font-size: .82rem; }
.empty-orbit { color: var(--oxford-700); font-family: var(--font-serif); font-size: 1.5rem; letter-spacing: .13em; }
.result-content { padding-top: 22px; }
.result-equation { color: var(--muted); font-size: .78rem; font-weight: 650; }
.result-matrices {
  margin-top: 14px;
  padding: 22px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 20px 30px;
  border: 1px solid #e0e8ee;
  border-radius: 16px;
  background: #f8fafc;
}
.result-matrix-group { display: flex; align-items: center; gap: 14px; }
.result-matrix-group > strong { color: var(--oxford-700); font-family: var(--font-serif); font-weight: 600; }
.result-separator { color: #91a4b6; }
.matrix-display {
  position: relative;
  padding: 9px 17px;
  min-width: 68px;
  display: grid;
  place-items: center;
  color: var(--oxford-950);
  font-family: var(--font-serif);
  font-size: 1.12rem;
  font-variant-numeric: tabular-nums;
  text-align: center;
}
.matrix-display::before, .matrix-display::after {
  content: "";
  position: absolute;
  inset-block: 0;
  width: 8px;
  border: 2px solid var(--oxford-700);
}
.matrix-display::before { left: 0; border-right: 0; border-radius: 7px 0 0 7px; }
.matrix-display::after { right: 0; border-left: 0; border-radius: 0 7px 7px 0; }
.matrix-display.is-typeset::before, .matrix-display.is-typeset::after { display: none; }
.math-rendered mjx-container { color: inherit; }
.matrix-display mjx-container[display="true"] { margin: 0 !important; }
.matrix-display mjx-container svg { max-width: min(100%, 720px); height: auto; overflow: visible; }
.inline-math {
  display: inline-block;
  margin-inline: .08em;
  color: inherit;
  line-height: 1;
  vertical-align: -.12em;
}
.inline-math mjx-container { margin: 0 !important; }
.result-equation .inline-math, .step-list .inline-math { color: var(--oxford-800); }
.learning-details { margin-top: 18px; display: grid; grid-template-columns: 1fr 1fr; gap: 11px; }
details { border-bottom: 1px solid var(--line); }
details summary { list-style: none; cursor: pointer; }
details summary::-webkit-details-marker { display: none; }
.learning-details details {
  padding: 0 16px;
  border: 1px solid #dbe5ec;
  border-radius: 14px;
  background: white;
  transition: border-color .16s ease, background .16s ease;
}
.learning-details details[open] { border-color: #b9cfdf; background: #f8fbfd; }
.learning-details summary { min-height: 62px; display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.learning-details summary span:first-child { display: grid; gap: 2px; }
.learning-details summary strong { color: var(--oxford-900); font-size: .78rem; }
.learning-details summary small { color: var(--muted); font-size: .64rem; font-weight: 450; }
.learning-details summary > span:last-child { color: var(--teal); font-size: 1.15rem; transition: transform .18s ease; }
.learning-details details[open] summary > span:last-child { transform: rotate(45deg); }
.details-body { padding: 0 0 16px; color: var(--muted); font-size: .82rem; line-height: 1.65; }
.details-body p:last-child { margin-bottom: 0; }
.step-list { margin: 0; padding: 0 0 16px 24px; color: var(--muted); font-size: .75rem; line-height: 1.55; }
.step-list li + li { margin-top: 8px; }
.step-list li::marker { color: var(--teal); font-weight: 800; }

/* Visual workspaces */
.visual-layout { display: grid; grid-template-columns: minmax(0, 1.55fr) minmax(315px, .62fr); gap: 18px; }
.canvas-panel { overflow: hidden; border-color: #cbd7e1; }
.visual-toolbar { min-height: 88px; padding: 16px 20px; border-bottom: 1px solid var(--line); background: #f8fafc; }
.toolbar-select { display: flex; align-items: center; gap: 11px; }
.toolbar-label { color: var(--oxford-700); font-size: .61rem; font-weight: 850; text-transform: uppercase; letter-spacing: .11em; }
.visual-toolbar label { display: flex; align-items: center; gap: 9px; }
.visual-toolbar select { min-width: 150px; }
.toolbar-actions { display: flex; flex-wrap: wrap; align-items: center; justify-content: flex-end; gap: 10px; }
.preset-row { display: flex; flex-wrap: wrap; justify-content: flex-end; gap: 6px; }
.preset-button { min-height: 34px; border-color: #c9d5df; border-radius: 9px; color: #486079; }
.preset-button:hover { border-color: #88a9c0; background: var(--teal-soft); color: var(--oxford-900); }
.transform-feature-controls {
  margin: 0;
  padding: 3px;
  display: inline-flex;
  align-items: center;
  gap: 3px;
  border: 1px solid #c9d5df;
  border-radius: 11px;
  background: white;
}
.visual-toolbar .feature-toggle {
  min-height: 30px;
  padding: 5px 8px;
  display: inline-flex;
  grid-template-columns: none;
  flex-direction: row;
  align-items: center;
  justify-content: center;
  gap: 6px;
  border-radius: 7px;
  color: var(--oxford-700);
  font-size: .66rem;
  font-weight: 800;
  line-height: 1;
  white-space: nowrap;
  cursor: pointer;
  transition: background .16s ease, color .16s ease;
}
.feature-toggle:hover { background: var(--teal-soft); color: var(--oxford-900); }
.feature-toggle:has(input:checked) { background: var(--oxford-900); color: white; }
.feature-toggle input { width: 15px; height: 15px; margin: 0; flex: 0 0 auto; accent-color: var(--gold); }
.zoom-controls {
  min-height: 36px;
  display: inline-flex;
  align-items: center;
  overflow: hidden;
  border: 1px solid #c9d5df;
  border-radius: 10px;
  background: white;
  white-space: nowrap;
}
.zoom-controls button { width: 34px; height: 34px; border: 0; background: transparent; color: var(--oxford-700); font-size: 1rem; font-weight: 850; }
.zoom-controls button:hover { background: var(--teal-soft); }
.zoom-controls span { min-width: 30px; color: var(--muted); font-size: .66rem; font-variant-numeric: tabular-nums; text-align: center; }
.basis-drag-guide {
  min-height: 64px;
  padding: 10px 20px;
  display: grid;
  grid-template-columns: minmax(220px, 1fr) auto;
  align-items: center;
  gap: 3px 16px;
  border-bottom: 1px solid var(--line);
  background: #f2f7fa;
  color: var(--muted);
}
.basis-drag-copy { min-width: 0; display: flex; align-items: center; gap: 10px; }
.basis-drag-icon {
  width: 31px;
  height: 31px;
  flex: 0 0 auto;
  display: grid;
  place-items: center;
  border-radius: 9px;
  background: var(--oxford-900);
  color: white;
  font-size: 1rem;
  font-weight: 800;
}
.basis-drag-copy strong, .basis-drag-copy span { display: block; }
.basis-drag-copy strong { color: var(--oxford-900); font-size: .7rem; }
.basis-drag-copy span { margin-top: 1px; font-size: .72rem; }
.basis-selector-group { display: flex; align-items: center; gap: 4px; }
.basis-selector-group > span { margin-right: 3px; color: var(--oxford-700); font-size: .7rem; font-weight: 850; text-transform: uppercase; letter-spacing: .07em; }
.basis-selector-group button {
  width: 34px;
  height: 32px;
  padding: 0;
  border: 1px solid #b9cbd9;
  border-radius: 8px;
  background: white;
  color: var(--oxford-700);
  font-family: var(--font-serif);
  font-size: .93rem;
  font-weight: 750;
}
.basis-selector-group button:hover { border-color: var(--oxford-700); background: var(--teal-soft); }
.basis-selector-group button[aria-pressed="true"] { border-color: var(--oxford-900); background: var(--oxford-900); color: white; }
.basis-drag-guide > small { grid-column: 1 / -1; color: #64788d; font-size: .7rem; text-align: right; }
.canvas-wrap { width: 100%; overflow: hidden; background: var(--paper); }
.canvas-wrap canvas { width: 100%; height: auto; min-height: 430px; max-height: 640px; display: block; touch-action: auto; }
.canvas-wrap.is-basis-editing canvas,
.canvas-wrap[data-basis-editing="true"] canvas,
#transform-canvas.is-basis-editing { cursor: grab; touch-action: none; }
.canvas-wrap.is-dragging canvas,
.canvas-wrap[data-basis-dragging="true"] canvas,
#transform-canvas.is-dragging { cursor: grabbing; touch-action: none; }
.animation-controls {
  min-height: 76px;
  padding: 15px 20px;
  display: flex;
  align-items: center;
  gap: 20px;
  border-top: 1px solid var(--line);
  background: white;
}
.animation-controls > label { flex: 1; display: grid; grid-template-columns: auto 1fr auto; align-items: center; gap: 12px; color: var(--muted); font-size: .72rem; font-weight: 650; }
.playback-controls { display: flex; align-items: center; gap: 10px; }
.playback-speed-control { margin: 0; padding: 0; display: flex; align-items: center; gap: 7px; border: 0; color: var(--muted); font-size: .7rem; font-weight: 720; }
.playback-speed-control legend { margin-right: 1px; padding: 0; color: var(--muted); }
.playback-speed-control label { display: inline-flex; align-items: center; gap: 3px; white-space: nowrap; cursor: pointer; }
.playback-speed-control input { width: 15px; height: 15px; margin: 0; accent-color: var(--oxford-700); }
input[type="range"] { accent-color: var(--oxford-700); }

.insight-panel {
  padding: 28px;
  border-color: rgba(255, 255, 255, .08);
  background: linear-gradient(155deg, var(--oxford-900), var(--oxford-950));
  color: white;
  box-shadow: var(--shadow-lg);
}
.insight-panel .kicker { color: #8fd0ee; }
.insight-panel h2 { margin: 13px 0 12px; color: white; font-family: var(--font-serif); font-size: 1.85rem; font-weight: 550; line-height: 1.12; }
.insight-panel > p:not(.kicker) { color: #c1cfdd; font-size: .82rem; line-height: 1.65; }
.insight-stats { margin: 25px 0; display: grid; grid-template-columns: 1fr 1fr; border-block: 1px solid rgba(255, 255, 255, .16); }
.insight-stats div { padding: 17px 0; }
.insight-stats div + div { padding-left: 18px; border-left: 1px solid rgba(255, 255, 255, .16); }
.insight-stats dt { color: #9eb3c7; font-size: .64rem; }
.insight-stats dd { margin: 4px 0 0; color: white; font-family: var(--font-serif); font-size: 1.45rem; }
.basis-readout { margin-bottom: 22px; display: grid; gap: 11px; }
.basis-readout > div { display: flex; align-items: center; gap: 11px; }
.basis-readout small, .basis-readout strong { display: block; }
.basis-readout small { color: #9eb3c7; font-size: .62rem; }
.basis-readout strong { margin-top: 2px; color: white; font-family: var(--font-serif); }
.basis-dot { width: 11px; height: 11px; border-radius: 50%; box-shadow: 0 0 0 4px rgba(255, 255, 255, .06); }
.basis-dot.x { background: var(--coral); }
.basis-dot.y { background: #66a9df; }
.basis-coordinate-editor, .eigen-direction-readout {
  margin-bottom: 18px;
  padding: 14px;
  border: 1px solid rgba(255, 255, 255, .14);
  border-radius: 13px;
  background: rgba(255, 255, 255, .055);
}
.basis-coordinate-heading { display: flex; align-items: baseline; justify-content: space-between; gap: 8px; }
.basis-coordinate-heading h3, .eigen-direction-heading h3 { margin: 0; color: white; font-size: .78rem; }
.basis-coordinate-heading > span { color: #8fb0c9; font-size: .68rem; font-weight: 750; text-transform: uppercase; letter-spacing: .06em; }
.basis-coordinate-editor > p { margin: 4px 0 11px; color: #9eb3c7; font-size: .7rem; line-height: 1.45; }
.basis-coordinate-groups { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
.basis-coordinate-group {
  min-width: 0;
  padding: 8px;
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) minmax(0, 1fr);
  align-items: end;
  gap: 6px;
  border-radius: 9px;
  background: rgba(255, 255, 255, .06);
}
.basis-coordinate-group > span { align-self: center; display: inline-flex; align-items: center; gap: 6px; color: white; font-family: var(--font-serif); font-size: .8rem; }
.basis-coordinate-group .basis-dot { width: 8px; height: 8px; box-shadow: none; }
.basis-coordinate-group label { display: grid; gap: 3px; color: #a9bdcf; font-size: .7rem; font-weight: 750; }
.basis-coordinate-group input {
  width: 100%;
  min-width: 0;
  height: 31px;
  padding: 0 7px;
  border: 1px solid rgba(255, 255, 255, .19);
  border-radius: 7px;
  background: rgba(255, 255, 255, .1);
  color: white;
  font-size: .75rem;
  font-variant-numeric: tabular-nums;
}
.basis-coordinate-group input:hover { border-color: rgba(255, 255, 255, .35); }
.eigen-direction-heading { display: flex; align-items: center; gap: 10px; }
.eigen-direction-heading > span {
  width: 30px;
  height: 30px;
  display: grid;
  place-items: center;
  border-radius: 8px;
  background: var(--gold);
  color: var(--oxford-950);
  font-family: var(--font-serif);
  font-size: 1rem;
  font-weight: 800;
}
.eigen-direction-heading small { display: block; margin-bottom: 1px; color: #91acc2; font-size: .56rem; text-transform: uppercase; letter-spacing: .07em; }
.eigen-direction-list { margin-top: 11px; display: grid; gap: 7px; }
.eigen-direction-list p { margin: 0; color: #bfd0df; font-size: .66rem; line-height: 1.5; }
.insight-panel details { padding: 13px 0; border-color: rgba(255, 255, 255, .15); color: #bed0df; font-size: .73rem; }
.insight-panel summary { color: #a9dcf2; font-weight: 780; }
.insight-panel details p { margin: 10px 0 0; line-height: 1.6; }

/* Vector controls */
.vector-panel { padding: 25px; }
.vector-toolbar h2 { margin: 0; }
.switch-label { display: flex !important; flex-direction: row !important; align-items: center; gap: 8px !important; }
.switch-label input { width: 18px; height: 18px; accent-color: var(--oxford-700); }
.vector-panel form { padding: 20px 0; border-bottom: 1px solid var(--line); }
.vector-panel input { width: 100%; min-height: 42px; padding: 0 11px; }
.vector-panel fieldset { margin: 16px 0; padding: 0; display: grid; grid-template-columns: 1fr 1fr; gap: 9px; border: 0; }
.vector-panel legend { margin-bottom: 8px; color: var(--oxford-900); font-size: .7rem; font-weight: 800; }
.vector-form-actions { display: flex; gap: 8px; }
.vector-form-actions .button.secondary { width: auto; }
.vector-form-actions .button.primary { flex: 1; }
.vector-panel form .button { display: flex; align-items: center; justify-content: space-between; }
.vector-list-wrap { padding-top: 18px; }
.vector-list-wrap .subheading-row > span { color: var(--muted); font-size: .66rem; }
.vector-list { margin: 12px 0 0; padding: 0; display: grid; gap: 6px; list-style: none; }
.vector-item {
  min-height: 54px;
  padding: 8px 5px;
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto auto auto;
  align-items: center;
  gap: 7px;
  border-bottom: 1px solid var(--line);
}
.vector-swatch { width: 10px; height: 10px; border-radius: 50%; }
.vector-item strong { color: var(--oxford-900); font-family: var(--font-serif); }
.vector-item small { display: block; overflow: hidden; color: var(--muted); font-size: .61rem; text-overflow: ellipsis; white-space: nowrap; }
.vector-item button { min-height: 32px; padding: 5px 6px; border: 0; border-radius: 7px; background: transparent; color: var(--muted); font-size: .67rem; }
.vector-item button:hover { background: var(--teal-soft); color: var(--oxford-700); }
.vector-item button:last-child:hover { background: var(--coral-soft); color: var(--danger); }
.vector-item.is-hidden { opacity: .5; }

/* Projection and SVD labs */
.lab-toolbar h2 { margin: 0; }
.lab-legend { display: flex; flex-wrap: wrap; justify-content: flex-end; gap: 8px 14px; color: var(--muted); font-size: .64rem; font-weight: 730; }
.lab-legend span { display: inline-flex; align-items: center; gap: 7px; white-space: nowrap; }
.legend-line { width: 24px; height: 0; display: inline-block; border-top: 2px dashed currentColor; }
.legend-line.l2 { color: var(--coral); }
.legend-line.l1 { color: var(--blue); border-top-style: dotted; }
.interaction-guide {
  min-height: 62px;
  padding: 11px 20px;
  display: flex;
  align-items: center;
  gap: 11px;
  border-bottom: 1px solid var(--line);
  background: #f2f7fa;
  color: var(--muted);
}
.interaction-icon {
  width: 31px;
  height: 31px;
  flex: 0 0 auto;
  display: grid;
  place-items: center;
  border-radius: 9px;
  background: var(--oxford-900);
  color: white;
  font-family: var(--font-serif);
  font-size: 1rem;
  font-weight: 800;
}
.interaction-guide strong, .interaction-guide span { display: block; }
.interaction-guide strong { color: var(--oxford-900); font-size: .7rem; }
.interaction-guide div > span { margin-top: 1px; font-size: .63rem; }
.projection-canvas-wrap { position: relative; }
.projection-canvas-wrap canvas { touch-action: auto; }
.projection-drag-handle {
  position: absolute;
  left: 0;
  top: 0;
  z-index: 2;
  width: 44px;
  height: 44px;
  padding: 0;
  border: 2px solid rgba(0, 33, 71, .42);
  border-radius: 50%;
  background: rgba(255, 255, 255, .08);
  cursor: grab;
  touch-action: none;
  transform: translate(-50%, -50%);
}
.projection-drag-handle:hover { border-color: var(--oxford-900); background: rgba(217, 237, 247, .18); }
.projection-drag-handle:active, .projection-canvas-wrap.is-dragging .projection-drag-handle { cursor: grabbing; }
.projection-drag-handle:focus-visible { z-index: 5; }
.projection-direction-handle { border-color: rgba(22, 76, 124, .72); border-radius: 12px; border-style: dashed; background: rgba(217, 237, 247, .1); }
.projection-target-handle { border-color: rgba(0, 33, 71, .52); border-radius: 50%; }
.projection-drag-handle.is-clustered { box-shadow: 0 3px 10px rgba(0, 33, 71, .13); }
.lab-input-bar {
  min-height: 92px;
  padding: 13px 20px;
  display: flex;
  align-items: center;
  gap: 15px 24px;
  border-top: 1px solid var(--line);
  background: white;
}
.coordinate-pair { margin: 0; padding: 0; display: grid; grid-template-columns: repeat(2, minmax(68px, 88px)); gap: 7px; border: 0; }
.coordinate-pair legend { grid-column: 1 / -1; margin-bottom: 2px; color: var(--oxford-900); font-size: .72rem; font-weight: 820; }
.coordinate-pair label { display: grid; grid-template-columns: auto minmax(0, 1fr); align-items: center; gap: 6px; color: var(--muted); font-size: .72rem; font-weight: 750; }
.coordinate-pair input { width: 100%; min-width: 0; height: 35px; padding: 0 8px; font-variant-numeric: tabular-nums; }
.lab-error { flex: 1; margin: 0; text-align: right; }
.projection-insight h2, .svd-insight h2 { font-size: 1.68rem; }
.lab-stats { margin-block: 21px; }
.norm-readouts { display: grid; gap: 12px; }
.norm-readouts section { padding: 13px 0; border-top: 1px solid rgba(255, 255, 255, .14); }
.norm-readouts section > div { display: flex; align-items: center; gap: 9px; }
.norm-readouts h3 { color: white; font-size: .76rem; }
.norm-readouts p { margin: 9px 0 0; display: flex; align-items: baseline; justify-content: space-between; gap: 12px; color: #9eb3c7; font-size: .62rem; }
.norm-readouts strong { color: white; font-family: var(--font-serif); font-size: .78rem; font-weight: 550; font-variant-numeric: tabular-nums; text-align: right; }
.norm-badge { width: 26px; height: 26px; display: grid; place-items: center; border-radius: 8px; color: white; font-family: var(--font-serif); font-weight: 800; }
.norm-badge.l2 { background: var(--coral); }
.norm-badge.l1 { background: var(--blue); }
.lab-note { margin: 15px 0 4px !important; padding: 10px 11px; border-left: 2px solid var(--gold); background: rgba(241, 180, 52, .08); color: #d5e0e9 !important; font-size: .68rem !important; line-height: 1.5 !important; }
.svd-stage-buttons { display: flex; flex-wrap: wrap; justify-content: flex-end; gap: 5px; }
.svd-stage-buttons button {
  min-height: 34px;
  padding: 6px 9px;
  border: 1px solid #c9d5df;
  border-radius: 9px;
  background: white;
  color: var(--muted);
  font-size: .72rem;
  font-weight: 780;
}
.svd-stage-buttons button:hover { border-color: #88a9c0; background: var(--teal-soft); color: var(--oxford-900); }
.svd-stage-buttons button[aria-pressed="true"] { border-color: var(--oxford-900); background: var(--oxford-900); color: white; }
.svd-controls {
  min-height: 88px;
  padding: 14px 20px;
  display: grid;
  grid-template-columns: auto minmax(220px, 1fr);
  align-items: center;
  gap: 15px 20px;
  border-top: 1px solid var(--line);
  background: white;
}
.svd-controls > label { display: grid; grid-template-columns: auto minmax(80px, 1fr) auto; align-items: center; gap: 9px; color: var(--muted); font-size: .72rem; font-weight: 700; }
.svd-controls output { min-width: 33px; color: var(--oxford-900); font-variant-numeric: tabular-nums; text-align: right; }
.svd-error { min-height: 0; padding: 0 20px 12px; background: white; }
.singular-values { margin: 20px 0 18px; display: grid; gap: 10px; }
.singular-values > div { display: grid; grid-template-columns: 24px 50px minmax(0, 1fr); align-items: center; gap: 8px; }
.singular-values span { color: #9eb3c7; font-family: var(--font-serif); font-size: .75rem; }
.singular-values strong { color: white; font-family: var(--font-serif); font-size: .88rem; font-variant-numeric: tabular-nums; }
.singular-values i { width: 0; max-width: 100%; height: 5px; display: block; border-radius: 99px; background: var(--coral); transition: width .22s ease; }
.singular-values > div + div i { background: #66a9df; }
.svd-factors { margin: 0; display: grid; gap: 8px; }
.svd-factors div { min-width: 0; padding: 9px 0; display: grid; grid-template-columns: 28px minmax(0, 1fr); gap: 8px; border-top: 1px solid rgba(255, 255, 255, .13); }
.svd-factors dt { color: #8fd0ee; font-family: var(--font-serif); font-weight: 800; }
.svd-factors dd { margin: 0; overflow-wrap: anywhere; color: white; font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: .65rem; font-variant-numeric: tabular-nums; line-height: 1.5; }
.svd-overview {
  margin: -8px 0 22px;
  padding: 18px 22px;
  display: grid;
  grid-template-columns: minmax(180px, .65fr) minmax(250px, 1fr) minmax(250px, 1fr);
  align-items: center;
  gap: 18px 28px;
  border: 1px solid #cddde8;
  border-radius: 17px;
  background: linear-gradient(135deg, #f4f8fb, #eaf3f8);
  color: var(--muted);
}
.svd-overview .kicker { margin: 0 0 5px; }
.svd-overview h2 { margin: 0; color: var(--oxford-900); font-family: var(--font-serif); font-size: 1.25rem; font-weight: 600; }
.svd-overview > p { margin: 0; font-size: .74rem; line-height: 1.55; }
.svd-overview strong { color: var(--oxford-900); }

/* Footer and dialog */
footer {
  min-height: 104px;
  padding: 22px 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 30px;
  border-top: 1px solid #ccd7e0;
  color: var(--muted);
  font-size: .69rem;
}
.footer-brand, .footer-actions { display: flex; align-items: center; gap: 13px; }
.footer-brand { align-items: flex-start; flex-direction: column; gap: 2px; }
.footer-brand strong { color: var(--oxford-900); font-size: .76rem; font-weight: 850; }
.footer-brand span { color: var(--muted); }
.footer-actions { justify-content: flex-end; }
dialog {
  width: min(440px, calc(100% - 28px));
  padding: 0;
  overflow: hidden;
  border: 1px solid #cbd7e1;
  border-radius: 20px;
  background: white;
  color: var(--ink);
  box-shadow: 0 30px 90px rgba(0, 25, 55, .3);
}
dialog::backdrop { background: rgba(0, 21, 47, .56); backdrop-filter: blur(4px); }
dialog form { padding: 28px; border-top: 5px solid var(--oxford-900); }
.dialog-heading p:not(.kicker) { margin: 8px 0 22px; color: var(--muted); font-size: .8rem; line-height: 1.55; }
.dialog-heading h2 { color: var(--oxford-900); font-size: 1.45rem; }
.dialog-actions { margin-top: 19px; display: flex; justify-content: flex-end; gap: 8px; }
dialog input { min-height: 44px; padding: 0 12px; }

@media (max-width: 1200px) {
  .topbar { grid-template-columns: 1fr auto; }
  .workspace-nav { grid-row: 2; grid-column: 1 / -1; justify-self: center; }
  .save-status { grid-column: 2; grid-row: 1; }
  .calculator-layout { grid-template-columns: minmax(200px, .62fr) minmax(390px, 1.38fr); }
  .operation-panel { grid-column: 1 / -1; min-height: auto; }
  .operation-panel .operation-picker { max-width: 640px; }
  .operation-panel .calculate-button { max-width: 390px; }
  .visual-layout { grid-template-columns: minmax(0, 1.2fr) minmax(290px, .65fr); }
  .visual-toolbar { align-items: flex-start; flex-direction: column; }
  .toolbar-actions { width: 100%; justify-content: space-between; }
  .preset-row { flex: 1; justify-content: flex-start; }
  .svd-controls { grid-template-columns: auto 1fr; }
  .svd-controls > label:last-child { grid-column: 2; }
}

@media (max-width: 900px) {
  .svd-overview { grid-template-columns: 1fr; gap: 9px; }
}

@media (max-width: 780px) {
  .page-shell { padding: 0 16px; }
  .topbar { top: 8px; margin-top: 8px; }
  .workspace-nav {
    width: 100%;
    padding: 6px;
    justify-content: flex-start;
    overflow-x: auto;
    scrollbar-width: thin;
  }
  .nav-tab { min-width: 86px; flex: 0 0 auto; padding-inline: 9px; }
  .nav-tab .tab-icon { display: none; }
  main { padding: 48px 0 58px; }
  .workspace-heading { grid-template-columns: 1fr; }
  .calculator-layout, .visual-layout { grid-template-columns: 1fr; }
  .library-panel, .editor-panel, .operation-panel { min-height: auto; }
  .library-panel { order: 1; }
  .editor-panel { order: 2; }
  .operation-panel { order: 3; grid-column: auto; }
  .matrix-library { max-height: none; grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .learning-details { grid-template-columns: 1fr; }
  .result-format-controls { align-items: flex-end; flex-direction: column; }
  .canvas-wrap canvas { min-height: 350px; }
  .insight-panel { order: 2; }
  .basis-drag-guide { grid-template-columns: minmax(200px, 1fr) auto; }
  .lab-input-bar { align-items: flex-start; flex-wrap: wrap; }
  .lab-error { flex-basis: 100%; text-align: left; }
  .svd-stage-buttons { width: 100%; justify-content: flex-start; }
  footer { flex-wrap: wrap; }
}

@media (max-width: 470px) {
  .page-shell { padding: 0 11px; }
  .topbar { padding: 9px; grid-template-columns: 1fr auto; border-radius: 16px; }
  .brand { padding-left: 3px; gap: 9px; }
  .brand-mark { width: 38px; height: 38px; }
  .brand-copy strong { font-size: .78rem; }
  .brand-copy small { margin-top: 3px; font-size: .53rem; }
  .save-status { display: none; }
  .workspace-nav { width: 100%; display: grid; grid-template-columns: repeat(6, minmax(0, 1fr)); overflow: visible; }
  .nav-tab { width: 100%; min-width: 0; grid-column: span 2; padding: 0 7px; gap: 3px; font-size: .68rem; }
  .nav-tab:nth-child(n + 4) { grid-column: span 3; }
  .nav-tab .tab-icon { width: 21px; height: 21px; }
  main { padding-top: 38px; }
  h1 { font-size: clamp(2.55rem, 13vw, 3.4rem); }
  .workspace-heading { margin-bottom: 25px; }
  .surface { border-radius: 19px; }
  .library-panel, .editor-panel, .operation-panel, .result-section, .insight-panel, .vector-panel { padding: 19px; }
  .editor-heading { display: block; }
  .dimension-controls { margin-top: 15px; }
  .matrix-editor-wrap { justify-content: flex-start; margin-inline: -3px; padding-inline: 5px; }
  .matrix-editor { grid-template-columns: repeat(var(--columns), 51px); }
  .matrix-cell { height: 43px; }
  .matrix-bracket { min-width: 9px; width: 9px; margin-inline: 4px; }
  .editor-actions { align-items: flex-start; flex-direction: column; }
  .editor-actions > div { justify-content: flex-start; }
  .operand-row { grid-template-columns: 1fr; }
  .result-heading { align-items: flex-start; flex-direction: column; }
  .result-format-controls { width: 100%; align-items: center; flex-direction: row; justify-content: space-between; }
  .result-matrices { padding: 18px 14px; overflow-x: auto; flex-wrap: nowrap; }
  .matrix-library { grid-template-columns: 1fr; }
  .toolbar-select { width: 100%; align-items: flex-start; flex-direction: column; gap: 4px; }
  .visual-toolbar label { width: 100%; justify-content: space-between; }
  .visual-toolbar select { flex: 1; min-width: 0; }
  .toolbar-actions { align-items: flex-start; flex-direction: column; }
  .preset-row { justify-content: flex-start; }
  .transform-feature-controls { width: 100%; }
  .visual-toolbar .feature-toggle { flex: 1; }
  .basis-drag-guide { padding: 10px 14px; grid-template-columns: 1fr auto; gap: 7px 10px; }
  .basis-drag-copy { grid-column: 1 / -1; }
  .basis-drag-guide > small { grid-column: 1; text-align: left; }
  .basis-selector-group { grid-column: 2; grid-row: 2; }
  .basis-selector-group > span { display: none; }
  .animation-controls { align-items: stretch; flex-direction: column; }
  .canvas-wrap canvas { min-height: 290px; }
  .lab-toolbar { align-items: flex-start; }
  .lab-legend { justify-content: flex-start; }
  .interaction-guide { padding-inline: 14px; }
  .lab-input-bar { display: grid; grid-template-columns: 1fr; padding-inline: 14px; }
  .coordinate-pair { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .svd-stage-buttons { width: 100%; display: grid; grid-template-columns: repeat(2, 1fr); }
  .svd-controls { grid-template-columns: 1fr; align-items: stretch; }
  .svd-controls > label, .svd-controls > label:last-child { grid-column: 1; }
  .svd-controls .button { width: 100%; }
  .playback-controls { align-items: flex-start; justify-content: space-between; flex-wrap: wrap; }
  .basis-coordinate-groups { grid-template-columns: 1fr; }
  .vector-item { grid-template-columns: auto minmax(90px, 1fr) auto auto auto; }
  footer { align-items: flex-start; flex-direction: column; gap: 18px; }
  .footer-actions { width: 100%; align-items: flex-start; justify-content: space-between; }
}

@media (max-width: 390px) {
  .nav-tab { gap: 2px; font-size: .7rem; }
  .nav-tab .tab-icon { display: none; }
  .result-format-controls { align-items: flex-start; flex-direction: column; }
  .vector-item { grid-template-columns: auto minmax(0, 1fr) auto; }
  .vector-item button { grid-row: 2; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    scroll-behavior: auto !important;
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
  }
}