/* ───────────────────────────────────────────────────────────
   Matrix Multiplication Simulator — tool-scoped styles
   Accent: #ff5252 (vibrant red) — unique in maths category
   ─────────────────────────────────────────────────────────── */

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg:        #0d1117;
  --surface:   #161b27;
  --surface2:  #1f2535;
  --border:    #2a3050;
  --accent:    #ff5252;
  --accent-lo: rgba(255, 82, 82, .22);
  --accent-hi: #ff8a80;
  --b-accent:  #4fc3f7;
  --c-accent:  #ffd54f;
  --green:     #3ddc84;
  --red:       #ff5555;
  --gold:      #f5c842;
  --text:      #dde3f0;
  --text-dim:  #6b7a99;
  --font:      'Segoe UI', system-ui, sans-serif;
  --mono:      'Courier New', monospace;
  --radius:    12px;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  min-height: 100vh;
  padding: 0 16px;
}

#app { max-width: 1100px; margin: 0 auto; display: flex; flex-direction: column; gap: 14px; padding: 12px 0 60px; }

/* ── Header ── */
header { text-align: center; padding: 4px 0; }
header h1 {
  font-size: 1.85rem; font-weight: 800;
  background: linear-gradient(120deg, var(--accent) 0%, var(--accent-hi) 100%);
  -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text;
}
.subtitle { color: var(--text-dim); font-size: 0.85rem; margin-top: 3px; }

/* ── Controls bar ── */
.controls-bar {
  display: flex; flex-wrap: wrap; align-items: center; gap: 14px;
  padding: 12px 16px;
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
}
.ctrl-group { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.ctrl-label {
  font-size: 0.72rem; text-transform: uppercase; letter-spacing: .06em;
  color: var(--text-dim); white-space: nowrap;
}

/* ── Pill tabs ── */
.pill-tabs { display: flex; background: var(--bg); border-radius: 8px; padding: 3px; gap: 2px; }
.pill {
  padding: 10px 14px; border: none; background: transparent; color: var(--text-dim);
  border-radius: 6px; cursor: pointer; font-size: 0.82rem; font-weight: 600;
  transition: background .18s, color .18s, box-shadow .18s;
  touch-action: manipulation; -webkit-tap-highlight-color: transparent;
  min-height: 44px;
}
.pill.active { background: var(--accent); color: #fff; box-shadow: 0 0 12px var(--accent-lo); }
.pill:hover:not(.active) { background: var(--surface2); color: var(--text); }

/* ── Buttons ── */
.btn {
  padding: 10px 16px; border: none; border-radius: 8px; cursor: pointer;
  font-size: 0.84rem; font-weight: 600; transition: filter .18s, box-shadow .18s, opacity .18s;
  touch-action: manipulation; -webkit-tap-highlight-color: transparent;
  min-height: 44px;
}
.btn:disabled { opacity: 0.4; cursor: not-allowed; }
.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:not(:disabled):hover { filter: brightness(1.12); box-shadow: 0 0 12px var(--accent-lo); }
.btn-ghost { background: var(--surface2); color: var(--text); border: 1px solid var(--border); }
.btn-ghost:hover { background: var(--border); }

/* ── Size selectors ── */
.size-pair {
  display: flex; align-items: center; gap: 6px;
  background: var(--bg); border: 1px solid var(--border); border-radius: 8px; padding: 4px 8px;
}
.size-select {
  background: var(--surface2); color: var(--accent); border: 1px solid var(--border);
  border-radius: 6px; padding: 4px 6px; font-family: var(--mono); font-weight: 700;
  font-size: 0.85rem; cursor: pointer; min-height: 28px;
}
.size-x { color: var(--text-dim); font-weight: 700; }
.size-fixed {
  background: var(--surface2); color: var(--b-accent); border: 1px dashed var(--border);
  border-radius: 6px; padding: 4px 10px; font-family: var(--mono); font-weight: 700;
  font-size: 0.85rem;
}
.size-select.locked,
.size-select:disabled {
  background: var(--bg); color: var(--text-dim);
  border-style: dashed; cursor: not-allowed; opacity: 0.85;
}
.locked-hint {
  display: inline-block;
  font-size: 0.66rem; font-weight: 700;
  color: var(--text-dim);
  background: rgba(255,255,255,.06);
  padding: 1px 6px; border-radius: 4px;
  margin: 0 2px;
  text-transform: none; letter-spacing: 0;
}

/* ── Preset chips ── */
.preset-bar { gap: 8px; }
.preset-chip {
  background: var(--surface2); color: var(--text); border: 1px solid var(--border);
  border-radius: 999px; padding: 7px 14px; font-size: 0.78rem; font-weight: 600;
  cursor: pointer; transition: all .18s;
  touch-action: manipulation; -webkit-tap-highlight-color: transparent;
}
.preset-chip:hover { background: var(--accent-lo); border-color: var(--accent); color: var(--accent); }
.preset-chip.active { background: var(--accent); color: #fff; border-color: var(--accent); }

/* ── Canvas card ── */
.canvas-card {
  position: relative;
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 10px;
  overflow-x: clip;
}
.canvas-card canvas {
  display: block; width: 100%; height: auto;
  touch-action: pan-y; cursor: crosshair;
}

/* ── Context menu ── */
.ctx-menu {
  position: absolute; z-index: 100; min-width: 180px;
  background: var(--surface); border: 1px solid var(--border); border-radius: 8px;
  padding: 4px 0; box-shadow: 0 8px 24px rgba(0,0,0,.5);
}
.ctx-item {
  display: block; width: 100%; padding: 8px 16px; border: none;
  background: transparent; color: var(--text); font-size: 0.82rem;
  text-align: left; cursor: pointer; transition: background .12s;
}
.ctx-item:hover { background: var(--accent-lo); color: var(--accent); }

/* ── Readout badges ── */
.readout-badges {
  display: flex; flex-wrap: wrap; gap: 8px;
  padding: 10px 14px;
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
}
.readout-badge {
  display: inline-flex; align-items: center; gap: 6px;
  background: var(--surface2); border: 1px solid var(--border);
  border-radius: 999px; padding: 5px 12px;
  font-size: 0.78rem; color: var(--text-dim);
}
.readout-badge strong { color: var(--text); font-family: var(--mono); font-weight: 700; }
.rb-dot { width: 8px; height: 8px; border-radius: 50%; display: inline-block; }

/* ── Matrix editors ── */
.matrix-editors {
  display: flex; align-items: center; justify-content: center;
  gap: 18px; flex-wrap: wrap;
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 14px;
}
.mtx-block {
  display: flex; flex-direction: column; gap: 8px; align-items: center;
}
.mtx-title {
  font-size: 0.85rem; font-weight: 600; color: var(--text-dim);
  display: flex; align-items: center; gap: 8px;
}
.mtx-name {
  font-family: var(--mono); font-weight: 800; font-size: 1.05rem;
  padding: 2px 10px; border-radius: 6px;
}
.mtx-name.a { background: rgba(255,82,82,.18); color: var(--accent); }
.mtx-name.b { background: rgba(79,195,247,.18); color: var(--b-accent); }
.mtx-name.c { background: rgba(255,213,79,.18); color: var(--c-accent); }
.mtx-shape {
  font-family: var(--mono); font-size: 0.78rem; color: var(--text-dim);
}
.mtx-times { font-size: 1.6rem; color: var(--text-dim); font-weight: 700; }

.mtx-grid {
  display: grid; gap: 4px;
  background: var(--bg); padding: 8px;
  border: 2px solid var(--border); border-radius: 8px;
  position: relative;
}
.mtx-cell {
  width: 48px; height: 36px;
  background: var(--surface2); color: var(--text);
  border: 1px solid var(--border); border-radius: 4px;
  font-family: var(--mono); font-size: 0.85rem; font-weight: 600;
  text-align: center; outline: none;
  transition: background .15s, border-color .15s, color .15s, transform .15s;
  -moz-appearance: textfield;
  padding: 0 4px;
}
.mtx-cell::-webkit-outer-spin-button,
.mtx-cell::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
.mtx-cell:focus { border-color: var(--accent); background: var(--bg); }
.mtx-cell.hl-row { background: rgba(255,82,82,.25); border-color: var(--accent); }
.mtx-cell.hl-col { background: rgba(79,195,247,.25); border-color: var(--b-accent); }
.mtx-cell.hl-pair { background: var(--accent); color: #fff; transform: scale(1.1); border-color: #fff; }
.mtx-cell.hl-pair.b-pair { background: var(--b-accent); }

.result-grid .mtx-cell { background: var(--surface); color: var(--text-dim); }
.result-grid .mtx-cell.done { background: rgba(255,213,79,.18); color: var(--c-accent); border-color: var(--c-accent); }
.result-grid .mtx-cell.flash {
  animation: flash 0.6s ease-out;
}
@keyframes flash {
  0%   { background: var(--c-accent); color: #000; transform: scale(1.3); box-shadow: 0 0 20px var(--c-accent); }
  100% { background: rgba(255,213,79,.18); color: var(--c-accent); transform: scale(1); box-shadow: none; }
}

.mtx-actions { display: flex; gap: 6px; }
.mtx-actions .btn { padding: 5px 10px; font-size: 0.74rem; min-height: 30px; }

/* ── Play / Action bar ── */
.play-bar {
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
  padding: 12px 16px;
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
}
.play-btn {
  padding: 11px 22px; border: 2px solid var(--accent); background: var(--accent);
  color: #fff; font-weight: 800; border-radius: 8px; cursor: pointer; font-size: 0.92rem;
  touch-action: manipulation; -webkit-tap-highlight-color: transparent;
  transition: filter .18s, box-shadow .18s;
}
.play-btn:hover { filter: brightness(1.1); box-shadow: 0 0 14px var(--accent-lo); }
.play-btn.playing { background: var(--surface2); color: var(--accent); }
.reset-btn {
  padding: 10px 16px; border: 2px solid var(--border); background: var(--surface2);
  color: var(--text); font-weight: 700; border-radius: 8px; cursor: pointer; font-size: 0.84rem;
  touch-action: manipulation; -webkit-tap-highlight-color: transparent;
}
.play-status { font-size: 0.84rem; font-weight: 600; color: var(--text-dim); margin-left: auto; }
.play-status.active { color: var(--green); }
.play-status.fail { color: var(--red); }

/* ── Formula panel ── */
.formula-panel {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 14px 16px;
}
.formula-title {
  font-size: 0.72rem; text-transform: uppercase; letter-spacing: .06em;
  color: var(--text-dim); margin-bottom: 8px;
}
.formula-row {
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
  font-family: var(--mono); font-size: 1rem;
}
.f-cell { color: var(--c-accent); font-weight: 700; }
.f-eq   { color: var(--text-dim); font-weight: 700; }
.f-expr { color: var(--text); flex: 1; min-width: 200px; word-break: break-word; }
.f-expr .term-a { color: var(--accent); font-weight: 700; }
.f-expr .term-b { color: var(--b-accent); font-weight: 700; }
.f-expr .term-mul { color: var(--text-dim); margin: 0 2px; }
.f-expr .term-plus { color: var(--text-dim); margin: 0 4px; }
.f-expr .term-running { color: var(--gold); font-weight: 700; padding: 2px 6px; background: rgba(245,200,66,.12); border-radius: 4px; }
.f-result { color: var(--green); font-weight: 800; font-size: 1.1rem; }

/* ── Result block ── */
.result-block {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 14px; display: flex; flex-direction: column; align-items: center; gap: 10px;
}

/* ── Explore panel ── */
.explore-panel {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 14px;
}
.explore-tabs {
  display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 14px;
  border-bottom: 1px solid var(--border); padding-bottom: 10px;
}
.explore-tab {
  background: var(--surface2); color: var(--text-dim); border: 1px solid var(--border);
  border-radius: 8px; padding: 8px 14px; font-size: 0.82rem; font-weight: 600;
  cursor: pointer; touch-action: manipulation; -webkit-tap-highlight-color: transparent;
  min-height: 36px;
}
.explore-tab.active { background: var(--accent); color: #fff; border-color: var(--accent); }
.explore-tab:hover:not(.active) { color: var(--text); }

.explore-cards {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 12px;
}
.explore-card {
  background: var(--bg); border: 1px solid var(--border); border-left: 3px solid var(--accent);
  border-radius: 8px; padding: 14px;
}
.explore-card h4 { color: var(--accent); font-size: 0.95rem; margin-bottom: 8px; }
.explore-card p { color: var(--text); font-size: 0.85rem; line-height: 1.55; margin-bottom: 8px; }
.explore-card .ex-formula {
  display: block; background: var(--surface2); padding: 8px 12px; border-radius: 6px;
  font-family: var(--mono); color: var(--gold); font-size: 0.85rem; margin: 8px 0;
}
.explore-card .ex-note {
  font-size: 0.78rem; color: var(--text-dim); font-style: italic; margin-top: 8px;
  padding-top: 8px; border-top: 1px dashed var(--border);
}

/* ── Practice panel ── */
.practice-panel {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 16px;
}
.pq-prompt { font-size: 1rem; color: var(--text); margin-bottom: 14px; font-weight: 600; }
.pq-prompt strong { color: var(--accent); }
.pq-matrices {
  display: flex; align-items: center; justify-content: center;
  gap: 14px; flex-wrap: wrap; margin: 14px 0;
}
.pq-answer {
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap; margin-top: 12px;
}
.pq-label { font-size: 0.85rem; color: var(--text-dim); }
.pq-label span { color: var(--c-accent); font-family: var(--mono); font-weight: 700; }
.pq-input {
  background: var(--bg); color: var(--accent); border: 1px solid var(--border);
  border-radius: 6px; padding: 8px 12px; font-family: var(--mono); font-weight: 700;
  font-size: 0.95rem; width: 130px; outline: none; min-height: 36px;
  -moz-appearance: textfield;
}
.pq-input::-webkit-outer-spin-button,
.pq-input::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
.pq-input:focus { border-color: var(--accent); box-shadow: 0 0 8px var(--accent-lo); }
.pq-feedback { margin-top: 12px; font-size: 0.9rem; font-weight: 700; min-height: 22px; }
.pq-feedback.ok { color: var(--green); }
.pq-feedback.err { color: var(--red); }
.pq-working {
  margin-top: 12px; padding: 12px 14px;
  background: var(--bg); border: 1px solid var(--border); border-left: 3px solid var(--gold);
  border-radius: 8px; font-family: var(--mono); font-size: 0.85rem; color: var(--text);
}
.practice-score {
  margin-top: 14px; padding-top: 12px; border-top: 1px solid var(--border);
  font-size: 0.85rem; color: var(--text-dim); text-align: right;
}
.practice-score strong { color: var(--text); font-family: var(--mono); }

/* ── Quiz panel ── */
.quiz-panel, .quiz-result {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 16px;
}
.quiz-head {
  display: flex; justify-content: space-between; align-items: center;
  font-size: 0.85rem; color: var(--text-dim); margin-bottom: 14px;
  padding-bottom: 10px; border-bottom: 1px solid var(--border);
}
.quiz-head strong { color: var(--text); font-family: var(--mono); }
.qz-body { margin-bottom: 14px; min-height: 120px; }
.qz-question { font-size: 1rem; color: var(--text); margin-bottom: 10px; font-weight: 600; }
.qz-matrices { display: flex; align-items: center; justify-content: center; gap: 12px; flex-wrap: wrap; margin: 12px 0; }
.qz-options { display: grid; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr)); gap: 8px; margin-top: 12px; }
.qz-option {
  background: var(--surface2); color: var(--text); border: 1px solid var(--border);
  border-radius: 8px; padding: 10px 14px; font-family: var(--mono); font-weight: 700;
  font-size: 0.92rem; cursor: pointer; transition: background .15s;
  touch-action: manipulation; -webkit-tap-highlight-color: transparent;
  min-height: 44px;
}
.qz-option:hover { background: var(--border); }
.qz-option.selected { background: var(--accent); color: #fff; border-color: var(--accent); }
.qz-option.correct { background: var(--green); color: #000; border-color: var(--green); }
.qz-option.wrong   { background: var(--red); color: #fff; border-color: var(--red); }
.qz-actions { display: flex; gap: 10px; flex-wrap: wrap; }
.qz-feedback { margin-top: 12px; font-size: 0.9rem; font-weight: 700; min-height: 20px; }
.qz-feedback.ok  { color: var(--green); }
.qz-feedback.err { color: var(--red); }

.qr-score-row { display: flex; align-items: center; justify-content: center; gap: 18px; margin-bottom: 16px; }
.qr-stars { font-size: 1.6rem; letter-spacing: 4px; }
.qr-stars.perfect { color: var(--gold); }
.qr-stars.good    { color: var(--green); }
.qr-stars.poor    { color: var(--red); }
.qr-score { font-family: var(--mono); font-size: 1.4rem; font-weight: 800; color: var(--text); }
.qr-breakdown { display: flex; flex-direction: column; gap: 6px; margin-bottom: 14px; }
.qr-row {
  display: flex; align-items: center; gap: 10px;
  padding: 8px 12px; background: var(--bg); border-radius: 6px; font-size: 0.82rem;
  border-left: 3px solid var(--border);
}
.qr-row.ok  { border-left-color: var(--green); }
.qr-row.err { border-left-color: var(--red); }
.qr-row .qr-q { flex: 1; color: var(--text); }
.qr-row .qr-mark { font-family: var(--mono); font-weight: 700; color: var(--text-dim); }
.qr-row.ok  .qr-mark { color: var(--green); }
.qr-row.err .qr-mark { color: var(--red); }

/* ── User Guide ── */
.user-guide {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 16px 20px;
}
.user-guide h2 { font-size: 1.2rem; color: var(--accent); margin-bottom: 12px; }
.user-guide details {
  border-top: 1px solid var(--border); padding: 10px 0;
}
.user-guide details:first-of-type { border-top: none; }
.user-guide summary {
  cursor: pointer; font-weight: 600; color: var(--text);
  display: flex; align-items: center; gap: 10px; padding: 4px 0;
}
.user-guide summary:hover { color: var(--accent); }
.user-guide details p,
.user-guide details ul { margin-top: 10px; font-size: 0.88rem; color: var(--text); line-height: 1.6; padding-left: 32px; }
.user-guide details ul { list-style-position: outside; }
.guide-section-num {
  background: var(--accent); color: #fff; border-radius: 999px;
  width: 22px; height: 22px; display: inline-flex; align-items: center; justify-content: center;
  font-size: 0.75rem; font-weight: 800; flex-shrink: 0;
}

/* ── SEO article ── */
.seo-article {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 18px 22px;
}
.seo-article h2 { font-size: 1.2rem; color: var(--accent); margin-bottom: 10px; }
.seo-article h3 { font-size: 1rem; color: var(--accent-hi); margin: 14px 0 8px; }
.seo-article p { font-size: 0.88rem; color: var(--text); line-height: 1.65; margin-bottom: 8px; }
.seo-article a { color: var(--accent); text-decoration: none; }
.seo-article a:hover { text-decoration: underline; }

/* ── Unified canvas (data entry + animation in one) ── */
.unified-canvas { position: relative; padding: 12px; min-height: 360px; }
.unified-canvas canvas { cursor: cell; height: auto; }
.cell-input {
  position: absolute; z-index: 50;
  box-sizing: border-box;
  background: #0d1117; color: var(--accent);
  border: 2px solid var(--accent); border-radius: 3px;
  font-family: var(--mono); font-weight: 700; font-size: 0.85rem;
  text-align: center; outline: none; padding: 0;
  -moz-appearance: textfield;
}
.cell-input::-webkit-outer-spin-button,
.cell-input::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }

/* Fill toolbar */
.fill-bar { padding: 8px 14px; gap: 16px; }
.fill-bar .ctrl-label { display: inline-flex; align-items: center; gap: 6px; }
.fill-bar .mtx-name { padding: 1px 7px; font-size: 0.78rem; }
.chip-mini {
  background: var(--surface2); color: var(--text); border: 1px solid var(--border);
  border-radius: 6px; padding: 5px 11px; font-family: var(--mono); font-weight: 700;
  font-size: 0.78rem; cursor: pointer; min-height: 30px;
  touch-action: manipulation; -webkit-tap-highlight-color: transparent;
  transition: all .15s;
}
.chip-mini:hover { background: var(--accent-lo); color: var(--accent); border-color: var(--accent); }
.fill-hint { margin-left: auto; }
.fill-hint-text { font-size: 0.78rem; color: var(--text-dim); font-style: italic; }
.size-b-hidden #fill-b-group { display: none; }

/* ── Operation tabs (primary nav within Simulate) ── */
.op-tabs .pill { padding: 9px 16px; font-size: 0.86rem; font-weight: 700; min-height: 40px; }
.op-tabs .pill[data-op="multiply"].active { background: #ff5252; }
.op-tabs .pill[data-op="add"].active      { background: #3ddc84; box-shadow: 0 0 12px rgba(61,220,132,.4); }
.op-tabs .pill[data-op="subtract"].active { background: #ffa726; box-shadow: 0 0 12px rgba(255,167,38,.4); }
.op-tabs .pill[data-op="inverse"].active  { background: #ab47bc; box-shadow: 0 0 12px rgba(171,71,188,.4); }
.op-tabs .pill[data-op="transpose"].active{ background: #26c6da; box-shadow: 0 0 12px rgba(38,198,218,.4); }

/* B block hide for inverse */
.matrix-editors.hide-b #b-block,
.matrix-editors.hide-b #mtx-op-symbol { display: none; }
.matrix-editors.hide-b { justify-content: center; }
.size-b-hidden #size-b-group { display: none; }

/* Operation symbol updates */
.mtx-times.is-plus  { color: #3ddc84; }
.mtx-times.is-minus { color: #ffa726; }

/* Step log for inverse */
.step-log {
  margin-top: 12px;
  padding: 10px 14px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-left: 3px solid #ab47bc;
  border-radius: 8px;
  max-height: 180px;
  overflow-y: auto;
  font-family: var(--mono);
  font-size: 0.82rem;
  color: var(--text);
}
.step-log .sl-row {
  padding: 4px 0;
  border-bottom: 1px dashed var(--border);
}
.step-log .sl-row:last-child { border-bottom: none; }
.step-log .sl-row.active { color: #ce93d8; font-weight: 700; }
.step-log .sl-row.done { color: var(--text-dim); }
.step-log .sl-num {
  display: inline-block; min-width: 28px; color: var(--text-dim);
}
.step-log .sl-op { color: #ce93d8; font-weight: 700; }

/* Cell highlight extras for add/sub */
.mtx-cell.hl-cellA { background: rgba(255,82,82,.45); color: #fff; border-color: var(--accent); transform: scale(1.08); }
.mtx-cell.hl-cellB { background: rgba(79,195,247,.45); color: #fff; border-color: var(--b-accent); transform: scale(1.08); }

/* Result block heading colour per op */
.mtx-name.c.is-add      { background: rgba(61,220,132,.18); color: var(--green); }
.mtx-name.c.is-subtract { background: rgba(255,167,38,.18); color: #ffa726; }
.mtx-name.c.is-inverse  { background: rgba(171,71,188,.18); color: #ce93d8; }
.mtx-name.c.is-transpose{ background: rgba(38,198,218,.18); color: #80deea; }

/* Responsive */
@media (max-width: 768px) {
  header h1 { font-size: 1.5rem; }
  .matrix-editors { gap: 10px; padding: 10px; }
  .mtx-cell { width: 40px; height: 32px; font-size: 0.78rem; }
  .mtx-times { font-size: 1.3rem; }
  .formula-row { font-size: 0.88rem; }
  .controls-bar { gap: 10px; padding: 10px 12px; }
  .pill { padding: 7px 11px; font-size: 0.78rem; }
}

@media (max-width: 500px) {
  body { padding: 0 10px; }
  header h1 { font-size: 1.3rem; }
  .subtitle { font-size: 0.74rem; }
  .mtx-cell { width: 34px; height: 30px; font-size: 0.74rem; padding: 0 2px; }
  .mtx-times { font-size: 1.1rem; }
  .preset-chip { padding: 6px 10px; font-size: 0.72rem; }
  .play-btn { padding: 10px 16px; font-size: 0.84rem; width: 100%; }
  .reset-btn { width: 100%; }
  .btn { width: 100%; }
  .play-bar .btn, .play-bar .play-btn, .play-bar .reset-btn { width: auto; flex: 1 1 calc(50% - 5px); }
  .play-status { width: 100%; margin-left: 0; text-align: center; }
  .controls-bar { gap: 8px; padding: 10px; }
  .pill { padding: 6px 10px; font-size: 0.74rem; min-height: 34px; }
  .readout-badges { padding: 8px; gap: 6px; }
  .readout-badge { font-size: 0.72rem; padding: 4px 9px; }
  .explore-cards { grid-template-columns: 1fr; }
}