:root {
  --ink: #142d39;
  --ink-soft: #35515c;
  --muted: #5d727a;
  --paper: #f4f7f5;
  --white: #ffffff;
  --line: #d8e1df;
  --line-dark: #83989a;
  --purple: #7652c7;
  --purple-dark: #52339e;
  --purple-soft: #eee9fa;
  --teal: #07988f;
  --teal-dark: #08726d;
  --teal-soft: #e3f5f2;
  --gold: #9b6910;
  --gold-soft: #fff3d6;
  --blue: #3977a8;
  --blue-soft: #e8f1f8;
  --shadow: 0 22px 60px rgba(19, 45, 57, 0.11);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  min-width: 320px;
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at 91% 6%, rgba(118, 82, 199, 0.1), transparent 30rem),
    radial-gradient(circle at 7% 35%, rgba(7, 152, 143, 0.06), transparent 24rem),
    linear-gradient(180deg, #fafcfb 0, var(--paper) 35rem);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  -webkit-font-smoothing: antialiased;
}

button { font: inherit; color: inherit; }

button:focus-visible,
a:focus-visible,
[tabindex]:focus-visible {
  outline: 3px solid rgba(7, 152, 143, 0.38);
  outline-offset: 3px;
}

[hidden] { display: none !important; }

.visually-hidden {
  position: absolute !important;
  width: 1px !important;
  height: 1px !important;
  padding: 0 !important;
  margin: -1px !important;
  overflow: hidden !important;
  clip: rect(0, 0, 0, 0) !important;
  white-space: nowrap !important;
  border: 0 !important;
}

.noscript-message {
  width: min(1380px, calc(100% - 3rem));
  margin: 1rem auto;
  padding: 0.85rem 1rem;
  border: 1px solid #d9414b;
  border-radius: 10px;
  color: #a92331;
  background: #fde8ea;
}

.skip-link {
  position: fixed;
  z-index: 500;
  top: 0.75rem;
  left: 0.75rem;
  transform: translateY(-180%);
  padding: 0.7rem 1rem;
  border-radius: 9px;
  color: white;
  background: var(--ink);
  text-decoration: none;
}

.skip-link:focus { transform: translateY(0); }

.site-header,
main,
footer {
  width: min(1380px, calc(100% - 3rem));
  margin-inline: auto;
}

.site-header {
  min-height: 68px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  border-bottom: 1px solid var(--line);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.75rem;
  color: var(--ink);
  font-size: 0.88rem;
  font-weight: 830;
  letter-spacing: -0.015em;
  text-decoration: none;
}

.brand-mark {
  width: 30px;
  height: 30px;
  display: grid;
  place-items: center;
  transform: rotate(-17deg);
  border: 3px solid var(--purple);
  border-radius: 50%;
}

.brand-mark i {
  width: 7px;
  height: 17px;
  border-radius: 99px;
  background: var(--teal);
}

.draft-pill {
  padding: 0.42rem 0.7rem;
  border: 1px solid #d8d0ee;
  border-radius: 999px;
  color: var(--purple-dark);
  background: rgba(255, 255, 255, 0.76);
  font-size: 0.61rem;
  font-weight: 860;
  letter-spacing: 0.1em;
  white-space: nowrap;
}

.intro {
  min-height: 165px;
  display: grid;
  grid-template-columns: minmax(0, 1.16fr) minmax(320px, 0.84fr);
  align-items: center;
  gap: 4rem;
  padding: 2rem 2.1rem 1.8rem;
}

.eyebrow,
.phase-name {
  margin: 0 0 0.48rem;
  color: var(--teal-dark);
  font-size: 0.65rem;
  font-weight: 880;
  letter-spacing: 0.135em;
  text-transform: uppercase;
}

h1, h2, h3, p { margin-top: 0; }

h1 {
  max-width: 820px;
  margin-bottom: 0;
  font-size: clamp(2.35rem, 4.55vw, 4.9rem);
  line-height: 0.96;
  letter-spacing: -0.069em;
}

h1 span { color: var(--teal); }

.intro-copy {
  max-width: 580px;
  margin: 1rem 0 0 auto;
  color: var(--ink-soft);
  font-size: clamp(0.95rem, 1.2vw, 1.08rem);
  line-height: 1.62;
}

.workbench-card {
  overflow: hidden;
  border: 1px solid rgba(174, 191, 189, 0.72);
  border-radius: 24px;
  background: rgba(255, 255, 255, 0.97);
  box-shadow: var(--shadow);
}

.workbench-header {
  min-height: 116px;
  display: grid;
  grid-template-columns: minmax(0, 1.12fr) minmax(390px, 0.88fr);
  align-items: center;
  gap: 2rem;
  padding: 1.2rem 1.55rem;
  border-bottom: 1px solid var(--line);
}

.status-copy {
  min-width: 0;
}

.status-copy h2 {
  margin-bottom: 0.28rem;
  font-size: clamp(1.35rem, 2vw, 2rem);
  line-height: 1.08;
  letter-spacing: -0.04em;
}

.status-copy > p:last-child {
  max-width: 780px;
  margin-bottom: 0;
  color: var(--ink-soft);
  font-size: 0.82rem;
  line-height: 1.45;
}

.metrics {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: #f8faf9;
}

.metrics div {
  min-width: 0;
  padding: 0.78rem 0.7rem 0.72rem;
  text-align: center;
}

.metrics div + div { border-left: 1px solid var(--line); }

.metrics span {
  display: block;
  font-size: 1.35rem;
  font-variant-numeric: tabular-nums;
  font-weight: 860;
  line-height: 1;
}

.metrics small {
  display: block;
  margin-top: 0.3rem;
  overflow: hidden;
  color: var(--muted);
  font-size: 0.58rem;
  font-weight: 790;
  letter-spacing: 0.055em;
  text-overflow: ellipsis;
  text-transform: uppercase;
  white-space: nowrap;
}

.simulation-layout {
  display: grid;
  grid-template-columns: minmax(560px, 1fr) 265px;
  min-height: 470px;
}

.stage-column {
  min-width: 0;
  display: grid;
  grid-template-rows: auto 1fr auto;
  padding: 1rem 1rem 0.75rem;
  background: white;
}

.stage-toolbar {
  min-height: 32px;
  display: flex;
  align-items: center;
  gap: 1.1rem;
  padding: 0 0.35rem;
  color: var(--muted);
  font-size: 0.6rem;
  font-weight: 760;
  letter-spacing: 0.035em;
  text-transform: uppercase;
}

.stage-toolbar span { display: inline-flex; align-items: center; gap: 0.38rem; }

.legend-dot {
  width: 14px;
  height: 4px;
  display: inline-block;
  border-radius: 99px;
}

.legend-dot.duplex { background: linear-gradient(90deg, var(--purple), var(--teal)); }
.legend-dot.daughter { background: linear-gradient(90deg, var(--purple-dark), var(--teal-dark)); }
.legend-dot.fork { width: 8px; height: 8px; background: var(--gold); }

.reaction-stage {
  position: relative;
  min-height: 402px;
  overflow: hidden;
  border: 1px solid #ccd8d6;
  border-radius: 18px;
  background:
    radial-gradient(circle at 72% 18%, rgba(118, 82, 199, 0.07), transparent 18rem),
    linear-gradient(180deg, #fbfdfc, #f3f7f5);
  isolation: isolate;
}

.reaction-stage::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  opacity: 0.24;
  background-image: radial-gradient(#8ca09f 0.6px, transparent 0.7px);
  background-size: 18px 18px;
}

#topology-canvas {
  width: 100%;
  height: 100%;
  min-height: 402px;
  display: block;
}

.crossing-inspectors {
  position: absolute;
  inset: 0;
  z-index: 3;
  pointer-events: none;
}

.crossing-inspector {
  position: absolute;
  width: 36px;
  height: 36px;
  display: grid;
  place-items: center;
  transform: translate(-50%, -50%);
  border: 1px solid rgba(155, 105, 16, 0.38);
  border-radius: 50%;
  color: var(--gold);
  background: rgba(255, 250, 240, 0.95);
  box-shadow: 0 5px 15px rgba(20, 45, 57, 0.12);
  cursor: zoom-in;
  pointer-events: auto;
  transition: transform 140ms ease, background 140ms ease, box-shadow 140ms ease;
}

.crossing-inspector::before {
  content: "";
  position: absolute;
  inset: -5px;
  border-radius: 50%;
}

.crossing-inspector svg {
  width: 21px;
  height: 21px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
}

.crossing-inspector:hover,
.crossing-inspector:focus-visible,
.crossing-inspector[aria-expanded="true"] {
  transform: translate(-50%, -50%) scale(1.08);
  background: #fff3d6;
  box-shadow: 0 7px 20px rgba(155, 105, 16, 0.22);
}

.enzyme-action-marker {
  --enzyme-color: var(--teal-dark);
  --action-scale: 1;
  position: absolute;
  z-index: 5;
  min-width: 176px;
  display: flex;
  align-items: center;
  gap: 0.48rem;
  padding: 0.42rem 0.58rem;
  border: 1px solid color-mix(in srgb, var(--enzyme-color) 55%, white);
  border-radius: 12px;
  color: var(--ink);
  background: rgba(255, 255, 255, 0.97);
  box-shadow: 0 9px 24px rgba(20, 45, 57, 0.18);
  pointer-events: none;
  transform: translate(-50%, calc(-100% - 20px)) scale(var(--action-scale));
  transform-origin: 50% calc(100% + 20px);
  will-change: left, top, opacity, transform;
}

.enzyme-action-marker[hidden] { display: none; }
.enzyme-action-marker[data-enzyme="topo2"] { --enzyme-color: var(--purple-dark); }

.enzyme-action-marker[data-placement="left"] {
  transform: translate(calc(-100% - 24px), -50%) scale(var(--action-scale));
  transform-origin: calc(100% + 24px) 50%;
}

.enzyme-action-marker[data-placement="right"] {
  transform: translate(24px, -50%) scale(var(--action-scale));
  transform-origin: -24px 50%;
}

.enzyme-action-marker::after {
  content: "";
  position: absolute;
  top: 100%;
  left: calc(50% - 1px);
  width: 2px;
  height: 20px;
  background: linear-gradient(var(--enzyme-color), color-mix(in srgb, var(--enzyme-color) 30%, transparent));
}

.enzyme-action-marker::before {
  content: "";
  position: absolute;
  top: calc(100% + 17px);
  left: calc(50% - 4px);
  width: 8px;
  height: 8px;
  border: 2px solid white;
  border-radius: 50%;
  background: var(--enzyme-color);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--enzyme-color) 24%, transparent);
}

.enzyme-action-marker[data-placement="left"]::after,
.enzyme-action-marker[data-placement="right"]::after {
  top: calc(50% - 1px);
  width: 24px;
  height: 2px;
}

.enzyme-action-marker[data-placement="left"]::after { left: 100%; }
.enzyme-action-marker[data-placement="right"]::after { left: -24px; }

.enzyme-action-marker[data-placement="left"]::before,
.enzyme-action-marker[data-placement="right"]::before {
  top: calc(50% - 4px);
}

.enzyme-action-marker[data-placement="left"]::before { left: calc(100% + 21px); }
.enzyme-action-marker[data-placement="right"]::before { left: -29px; }

.enzyme-action-token {
  min-width: 43px;
  height: 30px;
  display: grid;
  place-items: center;
  border-radius: 8px;
  color: white;
  background: var(--enzyme-color);
  font-family: Georgia, serif;
  font-size: 0.68rem;
  font-weight: 900;
  letter-spacing: 0.02em;
}

.enzyme-action-copy { display: grid; gap: 0.08rem; }

.enzyme-action-copy small {
  color: var(--enzyme-color);
  font-size: 0.48rem;
  font-weight: 900;
  letter-spacing: 0.08em;
}

.enzyme-action-copy strong {
  color: var(--ink-soft);
  font-size: 0.56rem;
  font-weight: 850;
  letter-spacing: 0.025em;
}

.stage-note {
  margin: 0;
  padding: 0.62rem 0.35rem 0;
  display: flex;
  align-items: center;
  gap: 0.42rem;
  color: var(--muted);
  font-size: 0.62rem;
  font-weight: 710;
}

.stage-note > span {
  width: 7px;
  height: 7px;
  flex: 0 0 7px;
  border-radius: 50%;
  background: var(--teal);
  box-shadow: 0 0 0 4px rgba(7, 152, 143, 0.1);
}

.ledger-panel {
  min-width: 0;
  padding: 1.15rem 1rem 1rem;
  border-left: 1px solid var(--line);
  background: #fbfcfc;
}

.panel-heading h3,
.control-heading h3 {
  margin: 0;
  font-size: 1rem;
  letter-spacing: -0.025em;
}

.identity-card {
  margin-top: 1rem;
  padding: 0.85rem;
  border: 1px solid #d8d0ee;
  border-radius: 13px;
  background: linear-gradient(145deg, var(--purple-soft), #fff 78%);
}

.identity-card > span,
.conservation-row > span {
  color: var(--purple-dark);
  font-size: 0.57rem;
  font-weight: 880;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.identity-card p {
  margin: 0.45rem 0 0.68rem;
  font-size: 1.23rem;
  letter-spacing: -0.02em;
}

.identity-values {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.45rem;
}

.identity-values span {
  padding: 0.45rem;
  border: 1px solid rgba(118, 82, 199, 0.18);
  border-radius: 9px;
  color: var(--muted);
  background: rgba(255, 255, 255, 0.72);
  font-size: 0.68rem;
}

.identity-values strong {
  float: right;
  color: var(--ink);
  font-variant-numeric: tabular-nums;
}

.ledger-list {
  margin: 0.9rem 0 0;
}

.ledger-list > div {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.8rem;
  padding: 0.55rem 0.2rem;
  border-bottom: 1px solid var(--line);
}

.ledger-list dt { color: var(--muted); font-size: 0.68rem; }
.ledger-list dd { margin: 0; font-size: 0.8rem; font-variant-numeric: tabular-nums; font-weight: 850; }

.conservation-row {
  margin-top: 0.9rem;
  padding: 0.72rem 0.75rem;
  border-radius: 11px;
  color: var(--teal-dark);
  background: var(--teal-soft);
}

.conservation-row strong {
  display: block;
  margin-top: 0.32rem;
  font-size: 0.75rem;
  font-variant-numeric: tabular-nums;
}

.ledger-note {
  margin: 0.8rem 0 0;
  color: var(--muted);
  font-size: 0.61rem;
  line-height: 1.45;
}

.control-deck {
  display: grid;
  grid-template-columns: minmax(235px, 0.82fr) minmax(390px, 1.35fr) minmax(250px, 0.9fr);
  border-top: 1px solid var(--line);
}

.control-group {
  min-width: 0;
  padding: 1rem;
  background: white;
}

.control-group + .control-group { border-left: 1px solid var(--line); }

.control-heading {
  display: grid;
  grid-template-columns: 32px 1fr;
  align-items: center;
  gap: 0.6rem;
}

.control-heading > span {
  width: 32px;
  height: 32px;
  display: grid;
  place-items: center;
  border-radius: 9px;
  color: var(--purple-dark);
  background: var(--purple-soft);
  font-size: 0.59rem;
  font-weight: 900;
}

.control-heading .eyebrow { margin-bottom: 0.12rem; font-size: 0.56rem; }
.control-heading h3 { font-size: 0.88rem; }

.control-help {
  min-height: 2.5em;
  margin: 0.65rem 0 0.7rem;
  color: var(--muted);
  font-size: 0.64rem;
  line-height: 1.4;
}

.button-pair,
.topo-buttons {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.42rem;
}

.control-group button,
.reset-button,
.challenge-button {
  cursor: pointer;
  transition: border-color 150ms ease, color 150ms ease, background 150ms ease, transform 150ms ease, opacity 150ms ease;
}

.button-pair button,
.topo-buttons button,
.fork-control-grid button {
  min-width: 0;
  min-height: 54px;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.52rem 0.58rem;
  border: 1px solid var(--line);
  border-radius: 11px;
  background: #fff;
  text-align: left;
}

.button-pair button:hover:not(:disabled),
.fork-control-grid button:hover:not(:disabled) {
  border-color: var(--purple);
  color: var(--purple-dark);
  background: var(--purple-soft);
}

.button-pair button:active:not(:disabled),
.fork-control-grid button:active:not(:disabled),
.topo-buttons button:active:not(:disabled) { transform: translateY(1px); }

.button-icon {
  width: 28px;
  height: 28px;
  flex: 0 0 28px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  color: var(--purple-dark);
  background: var(--purple-soft);
  font-size: 1rem;
  font-weight: 850;
}

.control-group button small,
.control-group button strong { display: block; }

.control-group button small {
  color: var(--muted);
  font-size: 0.53rem;
  font-weight: 840;
  letter-spacing: 0.065em;
}

.control-group button strong {
  margin-top: 0.12rem;
  overflow: hidden;
  font-size: 0.68rem;
  line-height: 1.15;
  text-overflow: ellipsis;
}

.fork-control-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.42rem;
}

.fork-control-grid button {
  min-height: 45px;
  display: block;
  text-align: center;
}

.fork-control-grid .transfer-button {
  border-color: #bfddda;
  background: #f6fbfa;
}

.fork-control-grid .transfer-button:hover:not(:disabled) {
  border-color: var(--teal);
  color: var(--teal-dark);
  background: var(--teal-soft);
}

.topo-buttons button { border-color: #bfddda; background: #f8fcfb; }
.topo-buttons button:hover:not(:disabled) { border-color: var(--teal); color: var(--teal-dark); background: var(--teal-soft); }

.topo-glyph {
  width: 28px;
  height: 28px;
  flex: 0 0 28px;
  display: grid;
  place-items: center;
  border: 2px solid var(--teal);
  border-radius: 8px;
  color: var(--teal-dark);
  background: white;
  font-family: Georgia, serif;
  font-size: 0.72rem;
  font-weight: 900;
}

button:disabled {
  cursor: not-allowed;
  opacity: 0.38;
}

.mechanism-strip {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr)) auto;
  border-top: 1px solid var(--line);
  background: #fbfcfc;
}

.mechanism-strip > div {
  min-height: 76px;
  display: flex;
  align-items: center;
  gap: 0.65rem;
  padding: 0.75rem 0.9rem;
}

.mechanism-strip > div + div { border-left: 1px solid var(--line); }

.mechanism-strip > div > span {
  width: 26px;
  height: 26px;
  flex: 0 0 26px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  color: var(--teal-dark);
  background: var(--teal-soft);
  font-size: 0.58rem;
  font-weight: 900;
}

.mechanism-strip p { margin: 0; }
.mechanism-strip strong, .mechanism-strip small { display: block; }
.mechanism-strip strong { font-size: 0.7rem; }
.mechanism-strip small { margin-top: 0.12rem; color: var(--muted); font-size: 0.59rem; line-height: 1.3; }

.reset-button {
  min-width: 112px;
  padding: 0.5rem 0.85rem;
  border: 0;
  border-left: 1px solid var(--line);
  color: var(--ink-soft);
  background: white;
  font-size: 0.67rem;
  font-weight: 810;
}

.reset-button:hover { color: var(--teal-dark); background: var(--teal-soft); }

.challenge-card {
  margin: 1.2rem 0;
  display: grid;
  grid-template-columns: minmax(330px, 1fr) minmax(390px, 1.2fr) auto;
  align-items: center;
  gap: 1.4rem;
  padding: 1.05rem 1.2rem;
  border: 1px solid #d8d0ee;
  border-radius: 18px;
  background: linear-gradient(135deg, rgba(238, 233, 250, 0.8), rgba(255, 255, 255, 0.95));
}

.challenge-copy h2 { margin-bottom: 0.35rem; font-size: 1.25rem; letter-spacing: -0.035em; }
.challenge-copy > p:last-child { margin: 0; color: var(--ink-soft); font-size: 0.7rem; line-height: 1.45; }

.challenge-progress {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  overflow: hidden;
  border: 1px solid rgba(118, 82, 199, 0.2);
  border-radius: 12px;
  background: rgba(255, 255, 255, 0.72);
}

.challenge-progress span {
  min-height: 50px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.36rem;
  padding: 0.45rem;
  color: var(--muted);
  font-size: 0.59rem;
  font-weight: 780;
  text-align: center;
}

.challenge-progress span + span { border-left: 1px solid rgba(118, 82, 199, 0.15); }

.challenge-progress i {
  width: 19px;
  height: 19px;
  flex: 0 0 19px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  color: var(--purple-dark);
  background: var(--purple-soft);
  font-size: 0.52rem;
  font-style: normal;
}

.challenge-progress span.is-complete { color: var(--teal-dark); background: rgba(227, 245, 242, 0.65); }
.challenge-progress span.is-complete i { color: white; background: var(--teal); }

.challenge-button {
  min-height: 42px;
  padding: 0.65rem 0.95rem;
  border: 1px solid var(--purple-dark);
  border-radius: 10px;
  color: white;
  background: var(--purple-dark);
  font-size: 0.67rem;
  font-weight: 840;
  white-space: nowrap;
}

.challenge-button:hover { border-color: var(--purple); background: var(--purple); }

.toast {
  position: fixed;
  z-index: 100;
  right: 1.25rem;
  bottom: 1.25rem;
  max-width: 390px;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.85rem 1rem;
  border: 1px solid #9ccfc7;
  border-radius: 13px;
  color: white;
  background: rgba(20, 45, 57, 0.96);
  box-shadow: 0 18px 40px rgba(20, 45, 57, 0.25), inset 4px 0 0 var(--teal);
}

.toast > span {
  width: 28px;
  height: 28px;
  flex: 0 0 28px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  color: var(--ink);
  background: #8ee0d6;
  font-weight: 900;
}

.toast p { margin: 0; font-size: 0.7rem; line-height: 1.4; }

footer {
  padding: 0.5rem 1.3rem 1.8rem;
  color: var(--muted);
  font-size: 0.63rem;
  line-height: 1.5;
}

footer p { max-width: 1000px; margin: 0; }
footer a { color: var(--teal-dark); }

@media (max-width: 1100px) {
  .simulation-layout { grid-template-columns: minmax(500px, 1fr) 235px; }
  .control-deck { grid-template-columns: 1fr 1.35fr; }
  .control-group:last-child { grid-column: 1 / -1; border-top: 1px solid var(--line); border-left: 0; }
  .control-group:last-child .topo-buttons { max-width: 520px; }
  .challenge-card { grid-template-columns: 1fr auto; }
  .challenge-progress { grid-column: 1 / -1; grid-row: 2; }
}

@media (max-width: 820px) {
  .site-header, main, footer { width: min(100% - 1.5rem, 1380px); }
  .intro { min-height: 0; grid-template-columns: 1fr; gap: 1rem; padding: 2rem 0.5rem; }
  .intro-copy { margin: 0; }
  .workbench-header { grid-template-columns: 1fr; gap: 1rem; }
  .simulation-layout { grid-template-columns: 1fr; }
  .ledger-panel { border-top: 1px solid var(--line); border-left: 0; }
  .ledger-panel { display: grid; grid-template-columns: 1fr 1fr; gap: 0 1rem; }
  .ledger-panel .panel-heading, .ledger-note { grid-column: 1 / -1; }
  .identity-card { margin-top: 0.7rem; }
  .control-deck { grid-template-columns: 1fr; }
  .control-group + .control-group, .control-group:last-child { grid-column: auto; border-top: 1px solid var(--line); border-left: 0; }
  .mechanism-strip { grid-template-columns: 1fr; }
  .mechanism-strip > div + div, .reset-button { border-top: 1px solid var(--line); border-left: 0; }
  .reset-button { min-height: 48px; }
}

@media (max-width: 600px) {
  .draft-pill { display: none; }
  h1 { font-size: clamp(2.35rem, 15vw, 3.9rem); }
  .workbench-header { padding: 1rem; }
  .metrics { grid-template-columns: repeat(3, 1fr); }
  .metrics div { padding-inline: 0.35rem; }
  .metrics span { font-size: 1.05rem; }
  .metrics small { font-size: 0.5rem; }
  .stage-column { padding: 0.7rem; }
  .stage-toolbar { flex-wrap: wrap; gap: 0.45rem 0.8rem; padding-bottom: 0.4rem; }
  .reaction-stage { min-height: 330px; overflow-x: auto; }
  #topology-canvas { min-width: 720px; min-height: 330px; }
  .ledger-panel { grid-template-columns: 1fr; }
  .ledger-panel .panel-heading, .ledger-note { grid-column: auto; }
  .challenge-card { grid-template-columns: 1fr; }
  .challenge-progress { grid-column: auto; grid-row: auto; grid-template-columns: 1fr; }
  .challenge-progress span + span { border-top: 1px solid rgba(118, 82, 199, 0.15); border-left: 0; }
  .challenge-button { width: 100%; }
  .toast { right: 0.75rem; bottom: 0.75rem; left: 0.75rem; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { scroll-behavior: auto !important; transition-duration: 0.01ms !important; }
}