:root {
  color-scheme: dark;
  --ss-bg: #081426;
  --ss-bg-soft: #0d1d34;
  --ss-surface: #112641;
  --ss-surface-2: #152d4c;
  --ss-line: #244567;
  --ss-text: #f4f8ff;
  --ss-muted: #aebed3;
  --ss-accent: #64d5ff;
  --ss-accent-rgb: 100, 213, 255;
  --ss-shadow: 0 18px 55px rgba(0, 0, 0, .28);
  --ss-font: Inter, ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

:root[data-theme="light"] {
  color-scheme: light;
  --ss-bg: #f5f8fc;
  --ss-bg-soft: #eaf2fb;
  --ss-surface: #fff;
  --ss-surface-2: #f6f9fd;
  --ss-line: #c9d8e8;
  --ss-text: #10243d;
  --ss-muted: #536b84;
  --ss-accent: #0878a5;
  --ss-accent-rgb: 8, 120, 165;
  --ss-shadow: 0 18px 48px rgba(36, 69, 103, .14);
}

body[data-subject="physics"] { --ss-accent: #45dfc3; --ss-accent-rgb: 69, 223, 195; }
body[data-subject="chemistry"] { --ss-accent: #ffb35c; --ss-accent-rgb: 255, 179, 92; }
body[data-subject="biology"] { --ss-accent: #76e58c; --ss-accent-rgb: 118, 229, 140; }
:root[data-theme="light"] body[data-subject="physics"] { --ss-accent: #087f70; --ss-accent-rgb: 8, 127, 112; }
:root[data-theme="light"] body[data-subject="chemistry"] { --ss-accent: #a85600; --ss-accent-rgb: 168, 86, 0; }
:root[data-theme="light"] body[data-subject="biology"] { --ss-accent: #257b36; --ss-accent-rgb: 37, 123, 54; }

html { scroll-behavior: smooth; }
body.sim-shell-ready {
  margin: 0 !important;
  padding: 0 20px 48px !important;
  min-height: 100vh;
  background: var(--ss-bg) !important;
  color: var(--ss-text) !important;
  font-family: var(--ss-font) !important;
  line-height: 1.5;
}
body.sim-shell-ready::before {
  content: "";
  position: fixed;
  inset: 0 0 auto;
  height: 580px;
  z-index: -1;
  pointer-events: none;
  background:
    radial-gradient(circle at 18% 8%, rgba(var(--ss-accent-rgb), .15), transparent 35%),
    radial-gradient(circle at 82% 4%, rgba(141, 124, 255, .14), transparent 30%);
}
body.sim-shell-ready *, body.sim-shell-ready *::before, body.sim-shell-ready *::after { box-sizing: border-box; }
body.sim-shell-ready a { color: inherit; }
body.sim-shell-ready button,
body.sim-shell-ready input,
body.sim-shell-ready select { font-family: var(--ss-font) !important; }
body.sim-shell-ready :focus-visible { outline: 3px solid var(--ss-accent) !important; outline-offset: 3px; }

.sim-skip {
  position: fixed;
  left: 14px;
  top: 12px;
  z-index: 3000;
  padding: 10px 14px;
  border-radius: 8px;
  background: var(--ss-text);
  color: var(--ss-bg) !important;
  transform: translateY(-180%);
  transition: transform .2s;
}
.sim-skip:focus { transform: translateY(0); }
.sim-shell-wide { width: min(1180px, 100%); margin-inline: auto; }

.sim-shell-nav {
  position: sticky;
  top: 0;
  z-index: 1000;
  margin: 0 -20px;
  border-bottom: 1px solid color-mix(in srgb, var(--ss-line) 75%, transparent);
  background: color-mix(in srgb, var(--ss-bg) 84%, transparent) !important;
  backdrop-filter: blur(18px);
}
.sim-shell-nav-inner {
  display: flex;
  align-items: center;
  gap: 22px;
  min-height: 70px;
}
.sim-shell-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  font-size: 1.25rem;
  font-weight: 850;
  letter-spacing: -.04em;
}
.sim-shell-brand-mark {
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  border: 1px solid var(--ss-line);
  border-radius: 12px;
  background: linear-gradient(145deg, var(--ss-surface-2), var(--ss-surface));
  box-shadow: 0 8px 25px rgba(0, 0, 0, .18);
}
.sim-shell-brand em { color: var(--ss-accent); font-style: normal; }
.sim-shell-brand small { color: var(--ss-muted); font-size: .68em; font-weight: 650; letter-spacing: -.01em; }
.sim-shell-links { display: flex; align-items: center; gap: 4px; margin-left: auto; }
.sim-shell-links a {
  padding: 8px 12px;
  border-radius: 9px;
  color: var(--ss-muted);
  text-decoration: none;
  font-size: .9rem;
  font-weight: 700;
}
.sim-shell-links a:hover { background: var(--ss-surface); color: var(--ss-text); }
.sim-theme-toggle {
  width: 42px !important;
  min-width: 42px;
  min-height: 40px;
  margin: 0 !important;
  padding: 0 !important;
  border: 1px solid var(--ss-line) !important;
  border-radius: 10px !important;
  background: var(--ss-surface) !important;
  color: var(--ss-text) !important;
  font-size: 1rem !important;
}

.sim-shell-hero { padding: 54px 0 28px; }
.sim-shell-crumbs { display: flex; align-items: center; gap: 8px; margin-bottom: 17px; color: var(--ss-muted); font-size: .82rem; }
.sim-shell-crumbs a { text-decoration: none; }
.sim-shell-crumbs a:hover { color: var(--ss-accent); }
.sim-shell-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin: 0 0 16px;
  padding: 7px 12px;
  border: 1px solid var(--ss-line);
  border-radius: 999px;
  background: color-mix(in srgb, var(--ss-surface) 80%, transparent);
  color: var(--ss-accent);
  font-size: .78rem;
  font-weight: 850;
  letter-spacing: .08em;
  text-transform: uppercase;
}
.sim-shell-eyebrow::before { content: ""; width: 8px; height: 8px; border-radius: 50%; background: var(--ss-accent); box-shadow: 0 0 16px var(--ss-accent); }
.sim-shell-hero-grid { display: grid; grid-template-columns: minmax(0, 1.3fr) minmax(280px, .7fr); gap: 28px; align-items: end; }
.sim-shell-hero h1 {
  margin: 0 !important;
  color: var(--ss-text) !important;
  font-size: clamp(2.2rem, 6vw, 4.5rem) !important;
  line-height: 1 !important;
  letter-spacing: -.06em;
  text-align: left !important;
  text-shadow: none !important;
}
.sim-shell-lede { max-width: 720px; margin: 18px 0 0; color: var(--ss-muted); font-size: clamp(1rem, 2vw, 1.16rem); }
.sim-shell-actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 23px; }
.sim-level-picker { display: inline-flex; gap: 4px; margin-top: 16px; padding: 4px; border: 1px solid var(--ss-line); border-radius: 12px; background: var(--ss-surface); }
.sim-level-picker button { min-height: 36px !important; margin: 0 !important; padding: 0 12px !important; border: 0 !important; border-radius: 8px !important; background: transparent !important; color: var(--ss-muted) !important; font-size: .78rem !important; font-weight: 850 !important; }
.sim-level-picker button[aria-pressed="true"] { background: var(--ss-text) !important; color: var(--ss-bg) !important; }
.sim-level-note { max-width: 720px; margin: 11px 0 0; color: var(--ss-muted); font-size: .84rem; }
.sim-shell-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 0 18px;
  border: 1px solid var(--ss-line);
  border-radius: 12px;
  background: var(--ss-surface);
  color: var(--ss-text) !important;
  text-decoration: none;
  font-weight: 800;
}
.sim-shell-button.primary { border-color: transparent; background: var(--ss-accent); color: var(--ss-bg) !important; }
.sim-shell-button:hover { transform: translateY(-2px); border-color: var(--ss-accent); }
.sim-shell-guide {
  padding: 20px;
  border: 1px solid var(--ss-line);
  border-radius: 18px;
  background: linear-gradient(145deg, var(--ss-surface-2), var(--ss-surface));
  box-shadow: var(--ss-shadow);
}
.sim-shell-guide strong { display: block; margin-bottom: 11px; color: var(--ss-text); }
.sim-shell-guide ol { display: grid; gap: 9px; margin: 0; padding: 0; list-style: none; counter-reset: steps; }
.sim-shell-guide li { display: grid; grid-template-columns: 28px 1fr; gap: 9px; align-items: center; color: var(--ss-muted); font-size: .88rem; }
.sim-shell-guide li::before { counter-increment: steps; content: counter(steps); display: grid; place-items: center; width: 27px; height: 27px; border-radius: 50%; background: rgba(var(--ss-accent-rgb), .13); color: var(--ss-accent); font-weight: 900; }
.sim-shell-assumptions { margin-top: 14px; padding-top: 13px; border-top: 1px solid var(--ss-line); color: var(--ss-muted); font-size: .8rem; }
.sim-shell-assumptions summary { color: var(--ss-text); cursor: pointer; font-weight: 800; }
.sim-shell-assumptions p { margin: 8px 0 0; }

body.sim-shell-ready > .container,
body.sim-shell-ready > main,
body.sim-shell-ready > section:not(.sim-shell-hero) { width: min(1180px, 100%) !important; max-width: 1180px !important; margin-inline: auto !important; }
body.sim-shell-ready > header:not(.sim-shell-nav)[hidden],
body.sim-shell-ready h1[hidden] { display: none !important; }
body.sim-shell-ready .panel,
body.sim-shell-ready .card,
body.sim-shell-ready .info-panel,
body.sim-shell-ready .controls,
body.sim-shell-ready .control-panel,
body.sim-shell-ready .data-panel,
body.sim-shell-ready .results,
body.sim-shell-ready .simulation-panel {
  border-color: var(--ss-line) !important;
  background-color: var(--ss-surface) !important;
  box-shadow: 0 9px 28px rgba(0, 0, 0, .12);
}
body.sim-shell-ready h2,
body.sim-shell-ready h3,
body.sim-shell-ready .control-group label,
body.sim-shell-ready .control-label,
body.sim-shell-ready .data-label { color: var(--ss-accent) !important; }
body.sim-shell-ready p,
body.sim-shell-ready li,
body.sim-shell-ready .info-text { line-height: 1.58; }
body.sim-shell-ready button:not(.sim-theme-toggle),
body.sim-shell-ready select,
body.sim-shell-ready input[type="number"],
body.sim-shell-ready input[type="text"] {
  border-color: var(--ss-line) !important;
  border-radius: 9px !important;
}
body.sim-shell-ready button:not(.sim-theme-toggle) { min-height: 42px; }
body.sim-shell-ready button:not(.sim-theme-toggle):hover { border-color: var(--ss-accent) !important; }
body.sim-shell-ready input[type="range"] { accent-color: var(--ss-accent); min-height: 24px; }
body.sim-shell-ready canvas,
body.sim-shell-ready svg { max-width: 100%; }
body.sim-shell-ready canvas { height: auto !important; border-color: var(--ss-line) !important; }

.sim-shell-footer {
  width: min(1180px, 100%);
  margin: 48px auto 0;
  padding: 28px 0 0;
  border-top: 1px solid var(--ss-line);
  color: var(--ss-muted);
}
.sim-shell-footer-inner { display: flex; align-items: center; justify-content: space-between; gap: 20px; }
.sim-shell-footer p { margin: 0; font-size: .84rem; }
.sim-shell-footer nav { display: flex; flex-wrap: wrap; gap: 15px; }
.sim-shell-footer a { color: var(--ss-muted); font-size: .84rem; text-decoration: none; }
.sim-shell-footer a:hover { color: var(--ss-accent); }

@media (max-width: 820px) {
  .sim-shell-hero-grid { grid-template-columns: 1fr; align-items: start; }
  .sim-shell-guide { max-width: 520px; }
  body.sim-shell-ready .main-content,
  body.sim-shell-ready .main,
  body.sim-shell-ready .top,
  body.sim-shell-ready .bot,
  body.sim-shell-ready .content,
  body.sim-shell-ready .top-row { grid-template-columns: minmax(0, 1fr) !important; }
}
@media (max-width: 620px) {
  body.sim-shell-ready { padding-inline: 14px !important; }
  .sim-shell-nav { margin-inline: -14px; }
  .sim-shell-nav-inner { min-height: 62px; gap: 8px; }
  .sim-shell-links a:not(:first-child) { display: none; }
  .sim-shell-brand { font-size: 1.05rem; }
  .sim-shell-brand-mark { width: 34px; height: 34px; }
  .sim-shell-hero { padding-top: 38px; }
  .sim-shell-hero h1 { font-size: clamp(2.2rem, 12vw, 3.25rem) !important; }
  .sim-level-picker { display: grid; grid-template-columns: repeat(3, 1fr); width: 100%; }
  .sim-shell-footer-inner { align-items: flex-start; flex-direction: column; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation: none !important; transition: none !important; }
}

/* Unified simulation workspace ------------------------------------------------ */
body.sim-shell-ready .sim-workspace {
  min-width: 0;
  padding: 0 !important;
  border: 0 !important;
  background: transparent !important;
  color: var(--ss-text) !important;
  box-shadow: none !important;
}
.sim-workspace-intro {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  margin: 0 0 16px;
  padding: 15px 18px;
  border: 1px solid var(--ss-line);
  border-radius: 16px;
  background: linear-gradient(120deg, rgba(var(--ss-accent-rgb), .1), var(--ss-surface));
}
.sim-workspace-intro div { display: grid; gap: 2px; }
.sim-workspace-intro span { color: var(--ss-accent); font-size: .7rem; font-weight: 900; letter-spacing: .1em; text-transform: uppercase; }
.sim-workspace-intro strong { color: var(--ss-text); font-size: 1.05rem; }
.sim-workspace-intro p { max-width: 620px; margin: 0; color: var(--ss-muted); font-size: .82rem; }
body.sim-shell-ready .sim-workspace > h1,
body.sim-shell-ready .sim-workspace > .subtitle,
body.sim-shell-ready .sim-workspace > .sub { display: none !important; }
body.sim-shell-ready .sim-legacy-footer { display: none !important; }

body.sim-shell-ready .sim-workspace :is(.main-content,.main-layout,.main-grid,.main,.content,.top,.bot,.top-row,.grid-2) {
  min-width: 0;
  gap: 18px !important;
}
body.sim-shell-ready .sim-workspace :is(
  .panel,.card,.info-panel,.controls-panel,.control-panel,.ctrl-panel,.controls,.data-panel,.results,
  .simulation-panel,.sim-panel,.canvas-panel,.canvas-section,.canvas-wrapper,.sidebar,.graph-panel,
  .graph-section,.concepts,.concepts-panel,.concepts-section,.concept-panel,.equation-panel,.readouts-panel,
  .anim-panel,.simulation-section
) {
  min-width: 0 !important;
  max-width: 100% !important;
  border: 1px solid var(--ss-line) !important;
  border-radius: 18px !important;
  background: linear-gradient(150deg, var(--ss-surface-2), var(--ss-surface)) !important;
  color: var(--ss-text) !important;
  box-shadow: 0 10px 30px rgba(0,0,0,.12) !important;
}
body.sim-shell-ready .sim-workspace :is(.data-item,.data-card,.data-box,.stat,.readout-item,.phase-box,.bubble-box,.circ-box,.lf-box,.concept-item,.concept-box,.info-box,.eq-box) {
  min-width: 0;
  border: 1px solid var(--ss-line) !important;
  border-radius: 12px !important;
  background: var(--ss-bg-soft) !important;
  color: var(--ss-text) !important;
  box-shadow: none !important;
}
body.sim-shell-ready .sim-workspace :is(.data-grid,.stats-row,.concepts-grid,.readouts-panel,.concentration-bar) { gap: 10px !important; }
body.sim-shell-ready .sim-workspace :is(.data-value,.data-val,.value,.val,.v,.d-val,.stat-val,.phase-val,.bubble-num,.readout-value,.control-value,.slider-value,.slider-val,.value-display,.val-display,.speed-display,.bar-value,.timer) {
  color: var(--ss-text) !important;
  font-variant-numeric: tabular-nums;
}
body.sim-shell-ready .sim-workspace :is(.data-label,.label,.lbl,.l,.d-label,.stat-label,.phase-label,.bubble-lbl,.readout-label,.ctrl-label,.slider-label,.bar-label,.mode-label) {
  color: var(--ss-muted) !important;
}
body.sim-shell-ready .sim-workspace :is(.panel-title,.sect-title,.sec-title,.concept-title,.equation-title,.data-title,.circ-title,.eq-title,.struct-name) {
  color: var(--ss-accent) !important;
  letter-spacing: .02em;
}
body.sim-shell-ready .sim-workspace :is(.info-text,.concept-def,.equation-text,.drag-hint,.status-message) { color: var(--ss-muted) !important; }
body.sim-shell-ready .sim-workspace :is(.equation,.equation-box,.eq-box,.info-box,.concept-box) {
  border-color: var(--ss-line) !important;
  background: rgba(var(--ss-accent-rgb), .08) !important;
}
body.sim-shell-ready .sim-workspace :is(.concept,.struct-info,.info-text,.val-display,.bar,.sample-checkbox,.mode-tabs) {
  border-color: var(--ss-line) !important;
  background: var(--ss-bg-soft) !important;
  color: var(--ss-text) !important;
  box-shadow: none !important;
}
body.sim-shell-ready .sim-workspace :is(.concept,.struct-info,.info-text,.val-display,.sample-checkbox,.mode-tabs) * {
  color: inherit;
}
body.sim-shell-ready .sim-workspace :is(.concept-term,.struct-name) { color: var(--ss-accent) !important; }
body[data-sim="photosynthesis-simulation"].sim-shell-ready .sim-workspace :is(.btn,.mbtn) {
  border-color: var(--ss-line) !important;
  background: var(--ss-surface-2) !important;
  color: var(--ss-text) !important;
}
body[data-sim="photosynthesis-simulation"].sim-shell-ready .sim-workspace :is(.btn,.mbtn).active {
  border-color: transparent !important;
  background: var(--ss-accent) !important;
  color: var(--ss-bg) !important;
}

body.sim-shell-ready .sim-workspace :is(select,input[type="number"],input[type="text"]) {
  width: 100% !important;
  min-height: 48px !important;
  padding: 9px 11px !important;
  border: 1px solid var(--ss-line) !important;
  border-radius: 10px !important;
  background: var(--ss-bg) !important;
  color: var(--ss-text) !important;
}
body.sim-shell-ready .sim-workspace input[type="range"] {
  width: 100% !important;
  min-width: 0 !important;
  min-height: 44px !important;
  margin: 0 !important;
  accent-color: var(--ss-accent);
  touch-action: pan-y;
}
body.sim-shell-ready .sim-workspace input[type="checkbox"],
body.sim-shell-ready .sim-workspace input[type="radio"] { width: 22px !important; height: 22px !important; min-width: 22px; accent-color: var(--ss-accent); }
body.sim-shell-ready .sim-workspace :is(.sample-checkbox,.chk-row,.checkbox-group label) {
  display: flex !important;
  align-items: center !important;
  gap: 10px !important;
  min-height: 46px !important;
  padding: 8px 10px !important;
  border: 1px solid var(--ss-line) !important;
  border-radius: 10px !important;
  background: var(--ss-bg-soft) !important;
  color: var(--ss-text) !important;
}
body.sim-shell-ready .sim-workspace :is(.sample-checkbox,.chk-row) label { display: flex; align-items: center; align-self: stretch; flex: 1; color: var(--ss-text) !important; cursor: pointer; }
body.sim-shell-ready .sim-workspace button:not(.sim-theme-toggle) {
  min-height: 46px !important;
  padding: 9px 14px !important;
  border: 1px solid var(--ss-line) !important;
  border-radius: 10px !important;
  background: var(--ss-surface-2) !important;
  color: var(--ss-text) !important;
  font-weight: 800 !important;
  touch-action: manipulation;
}
body.sim-shell-ready .sim-workspace button:is(.active,.btn-primary,.btn-start,.btn-go,.play-btn),
body.sim-shell-ready .sim-workspace button[aria-pressed="true"] { border-color: transparent !important; background: var(--ss-accent) !important; color: var(--ss-bg) !important; }
body.sim-shell-ready .sim-workspace :is(.button-group,.btn-row,.canvas-buttons,.export-buttons,.export-btns,.export-row,.mode-buttons,.mode-btns,.mode-tabs,.toggle-buttons,.toggle-group,.solvent-buttons) {
  display: flex !important;
  flex-wrap: wrap !important;
  gap: 8px !important;
}
body.sim-shell-ready .sim-workspace :is(.button-group,.btn-row,.canvas-buttons,.export-buttons,.export-btns,.export-row) > button { flex: 1 1 150px; }
body.sim-shell-ready .sim-workspace table { display: block; width: 100%; max-width: 100%; overflow-x: auto; color: var(--ss-text); }
body.sim-shell-ready .sim-workspace canvas,
body.sim-shell-ready .sim-workspace svg { display: block; width: 100% !important; max-width: 100% !important; height: auto !important; border-radius: 12px; }
body.sim-shell-ready .sim-workspace hr { border: 0; border-top: 1px solid var(--ss-line); }

/* Per-simulation structural repairs */
body[data-sim="chromatography-simulation"] .speed-control { display: flex !important; flex-wrap: wrap !important; min-width: 0 !important; width: 100% !important; }
body[data-sim="chromatography-simulation"] .speed-input { flex: 1 1 180px !important; min-width: 0 !important; width: 100% !important; }
body[data-sim="refraction-simulation"] .sim-panel { min-width: 0 !important; width: 100% !important; }
body[data-sim="titration-simulation"] .setup-section { min-width: 0 !important; }

@media (min-width: 821px) {
  body.sim-shell-ready .sim-primary-controls { position: sticky; top: 88px; align-self: start; }
}

@media (max-width: 820px) {
  body.sim-shell-ready .sim-workspace :is(.main-content,.main-layout,.main-grid,.main,.content,.top,.bot,.top-row,.grid-2) {
    display: grid !important;
    grid-template-columns: minmax(0,1fr) !important;
    width: 100% !important;
  }
  body[data-sim="titration-simulation"] .setup-section { grid-template-columns: minmax(0,1fr) !important; }
  body[data-sim="electrical-circuits-simulation"] .controls-panel,
  body[data-sim="diffusion-simulation"] .controls-panel { width: 100% !important; }
}

@media (max-width: 620px) {
  .sim-shell-hero { padding: 24px 0 18px; }
  .sim-shell-crumbs { margin-bottom: 10px; font-size: .75rem; }
  .sim-shell-eyebrow { margin-bottom: 10px; padding: 5px 9px; font-size: .68rem; }
  .sim-shell-hero h1 { font-size: clamp(2rem,10vw,2.75rem) !important; }
  .sim-shell-lede { margin-top: 12px; font-size: .95rem; }
  .sim-shell-actions { display: grid; grid-template-columns: 1fr; margin-top: 16px; }
  .sim-shell-actions .sim-shell-button:not(.primary) { display: none; }
  .sim-shell-guide { display: none; }
  .sim-level-picker { margin-top: 12px; }
  .sim-level-picker button { min-height: 44px !important; padding-inline: 6px !important; }
  .sim-workspace-intro { align-items: flex-start; flex-direction: column; gap: 6px; margin-bottom: 12px; padding: 12px 14px; }
  .sim-workspace-intro p { font-size: .78rem; }
  body.sim-shell-ready .sim-workspace :is(
    .panel,.card,.info-panel,.controls-panel,.control-panel,.ctrl-panel,.controls,.data-panel,.results,
    .simulation-panel,.sim-panel,.canvas-panel,.canvas-section,.canvas-wrapper,.sidebar,.graph-panel,
    .graph-section,.concepts,.concepts-panel,.concepts-section,.concept-panel,.equation-panel,.readouts-panel,
    .anim-panel,.simulation-section
  ) { padding: 14px !important; border-radius: 15px !important; }
  body.sim-shell-ready .sim-workspace :is(.data-grid,.stats-row,.concepts-grid,.readouts-panel,.concentration-bar,.setup-section,.samples-grid) {
    grid-template-columns: repeat(2,minmax(0,1fr)) !important;
  }
  body.sim-shell-ready .sim-workspace :is(.button-group,.btn-row,.canvas-buttons,.export-buttons,.export-btns,.export-row) > button { flex-basis: 100%; }
  body.sim-shell-ready .sim-workspace :is(.mode-buttons,.mode-btns,.mode-tabs,.toggle-buttons,.toggle-group,.solvent-buttons) > button { flex: 1 1 100px; }
  body.sim-shell-ready .sim-workspace canvas { min-height: 180px; object-fit: contain; }
  body[data-sim="atomic-structure-simulation"] #atomCanvas,
  body[data-sim="radioactive-decay-simulation"] #atomCvs,
  body[data-sim="refraction-simulation"] #simCanvas { min-height: 290px; }
  body[data-sim="titration-simulation"] .setup-section,
  body[data-sim="chromatography-simulation"] .samples-grid { grid-template-columns: minmax(0,1fr) !important; }
  .sim-shell-footer { margin-top: 30px; }
}