:root {
  color-scheme: dark;
  --page: #050816;
  --surface: #0b1428;
  --surface-strong: #111f38;
  --graph-ground: #071020;
  --ink: #f4fbff;
  --muted: #aebbd3;
  --line: rgba(173, 201, 238, 0.22);
  --cyan: #6fffe9;
  --blue: #7eb0ff;
  --amber: #ffd166;
  --danger: #ff9aa7;
  --shadow: 0 24px 70px rgba(0, 0, 0, 0.38);
}

:root[data-theme="light"] {
  color-scheme: light;
  --page: #eef2f8;
  --surface: #ffffff;
  --surface-strong: #e7eef8;
  --graph-ground: #f8fbff;
  --ink: #16213a;
  --muted: #4b5a75;
  --line: rgba(20, 32, 54, 0.2);
  --cyan: #087069;
  --blue: #2f5fd0;
  --amber: #8a5a00;
  --danger: #b41e36;
  --shadow: 0 24px 70px rgba(29, 46, 78, 0.16);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-width: 320px;
  min-height: 100vh;
  background:
    radial-gradient(circle at 14% 8%, color-mix(in srgb, var(--cyan) 11%, transparent), transparent 34rem),
    radial-gradient(circle at 91% 17%, color-mix(in srgb, var(--blue) 12%, transparent), transparent 31rem),
    var(--page);
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont,
    "Segoe UI", sans-serif;
}

button,
textarea {
  font: inherit;
}

button,
a {
  -webkit-tap-highlight-color: transparent;
}

button:focus-visible,
a:focus-visible,
textarea:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--cyan) 72%, transparent);
  outline-offset: 3px;
}

.lab-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  width: min(1500px, calc(100% - 2.5rem));
  margin: 0 auto;
  padding: 1.1rem 0;
  border-bottom: 1px solid var(--line);
}

.lab-brand {
  color: var(--cyan);
  font: 800 0.78rem/1 ui-monospace, SFMono-Regular, Menlo, monospace;
  letter-spacing: 0.11em;
  text-decoration: none;
}

.theme-toggle,
.arrange-button,
.primary-action,
.secondary-action {
  min-height: 2.75rem;
  border: 1px solid var(--line);
  border-radius: 0.8rem;
  cursor: pointer;
  font-weight: 800;
}

.theme-toggle,
.arrange-button,
.secondary-action {
  background: color-mix(in srgb, var(--surface-strong) 74%, transparent);
  color: var(--ink);
}

.theme-toggle,
.arrange-button {
  padding: 0.65rem 0.9rem;
  font-size: 0.8rem;
}

main {
  width: min(1500px, calc(100% - 2.5rem));
  margin: 0 auto;
  padding: clamp(2rem, 5vw, 4.8rem) 0 3rem;
}

.intro {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(22rem, 0.75fr);
  align-items: end;
  gap: 2rem;
  margin-bottom: 2rem;
}

.eyebrow {
  grid-column: 1 / -1;
  margin: 0 0 -1.25rem;
  color: var(--cyan);
  font: 800 0.78rem/1 ui-monospace, SFMono-Regular, Menlo, monospace;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

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

h1 {
  margin-bottom: 0;
  font-size: clamp(2.4rem, 5vw, 5rem);
  line-height: 0.98;
  letter-spacing: -0.045em;
}

.intro > p:last-child {
  margin-bottom: 0.15rem;
  color: var(--muted);
  font-size: clamp(1rem, 1.4vw, 1.22rem);
  line-height: 1.55;
}

.workspace {
  display: grid;
  grid-template-columns: minmax(17rem, 21rem) minmax(0, 1fr);
  gap: 1.1rem;
  align-items: stretch;
}

.input-panel,
.graph-panel {
  border: 1px solid var(--line);
  background: color-mix(in srgb, var(--surface) 95%, transparent);
  box-shadow: var(--shadow);
}

.input-panel {
  display: flex;
  flex-direction: column;
  padding: 1rem;
  border-radius: 1.15rem;
}

.input-heading,
.graph-heading {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.input-heading label,
.graph-heading h2 {
  font-size: 1.05rem;
  font-weight: 850;
}

.input-heading span {
  color: var(--cyan);
  font: 750 0.75rem/1 ui-monospace, SFMono-Regular, Menlo, monospace;
}

.input-hint,
.input-note,
.graph-heading output,
.selection-readout {
  color: var(--muted);
  line-height: 1.45;
}

.input-hint {
  margin: 0.55rem 0 0.8rem;
  font-size: 0.82rem;
}

textarea {
  width: 100%;
  min-height: 31rem;
  flex: 1 1 auto;
  resize: vertical;
  padding: 0.9rem;
  border: 1px solid var(--line);
  border-radius: 0.85rem;
  background: var(--graph-ground);
  color: var(--ink);
  font: 700 0.94rem/1.55 ui-monospace, SFMono-Regular, Menlo, monospace;
  letter-spacing: 0.06em;
}

.input-error {
  margin: 0.7rem 0 0;
  color: var(--danger);
  font-size: 0.82rem;
  font-weight: 750;
}

.form-actions {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.55rem;
  margin-top: 0.8rem;
}

.primary-action,
.secondary-action {
  width: 100%;
  padding: 0.72rem 0.9rem;
}

.primary-action {
  border-color: var(--cyan);
  background: var(--cyan);
  color: #06202a;
}

.input-note {
  margin: 0.8rem 0 0;
  font-size: 0.76rem;
}

.graph-panel {
  min-width: 0;
  padding: 1rem;
  border-radius: 1.15rem;
}

.graph-heading h2 {
  margin: 0 0 0.18rem;
}

.graph-heading output {
  display: block;
  min-height: 1.25rem;
  font-size: 0.82rem;
}

.graph-key {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem 1.1rem;
  margin: 0.8rem 0;
  color: var(--muted);
  font-size: 0.74rem;
}

.graph-key span {
  display: inline-flex;
  align-items: center;
  gap: 0.42rem;
}

.key-line {
  display: inline-block;
  width: 1.65rem;
  border-top: 2px solid var(--blue);
}

.key-line.one-way {
  border-top-style: dashed;
  opacity: 0.75;
}

.graph-stage {
  min-height: 38rem;
  height: min(70vh, 49rem);
  border: 1px solid var(--line);
  border-radius: 0.9rem;
  overflow: hidden;
  background:
    linear-gradient(var(--line) 1px, transparent 1px),
    linear-gradient(90deg, var(--line) 1px, transparent 1px),
    var(--graph-ground);
  background-size: 38px 38px;
}

#neighborGraph {
  display: block;
  width: 100%;
  height: 100%;
  touch-action: none;
}

.graph-edge {
  fill: none;
  stroke: var(--blue);
  stroke-width: 1.35;
  stroke-opacity: 0.42;
  transition: stroke 0.18s ease, stroke-opacity 0.18s ease, stroke-width 0.18s ease;
}

.graph-edge.one-way {
  stroke-dasharray: 5 5;
}

.edge-label {
  fill: var(--muted);
  stroke: var(--graph-ground);
  stroke-width: 5px;
  paint-order: stroke;
  font: 750 11px/1 ui-monospace, SFMono-Regular, Menlo, monospace;
  text-anchor: middle;
  dominant-baseline: central;
  pointer-events: none;
  transition: opacity 0.18s ease, fill 0.18s ease;
}

.graph-node {
  cursor: grab;
}

.graph-node:active {
  cursor: grabbing;
}

.graph-node rect {
  fill: var(--surface-strong);
  stroke: color-mix(in srgb, var(--cyan) 62%, var(--line));
  stroke-width: 1.5;
  rx: 9;
  transition: fill 0.18s ease, stroke 0.18s ease, opacity 0.18s ease;
}

.graph-node text {
  fill: var(--ink);
  font: 750 12px/1 ui-monospace, SFMono-Regular, Menlo, monospace;
  text-anchor: middle;
  dominant-baseline: central;
  pointer-events: none;
}

.graph-node.is-selected rect {
  fill: var(--amber);
  stroke: var(--amber);
}

.graph-node.is-selected text {
  fill: #241900;
}

.graph-node.is-neighbor rect {
  fill: color-mix(in srgb, var(--cyan) 22%, var(--surface-strong));
  stroke: var(--cyan);
}

.graph-edge.is-active {
  stroke: var(--cyan);
  stroke-width: 2.7;
  stroke-opacity: 0.95;
}

.edge-label.is-active {
  fill: var(--ink);
  opacity: 1;
}

.graph-edge.is-dim,
.edge-label.is-dim {
  opacity: 0.12;
}

.graph-node.is-dim rect,
.graph-node.is-dim text {
  opacity: 0.42;
}

.selection-readout {
  min-height: 2.75rem;
  margin: 0.75rem 0 0;
  font-size: 0.84rem;
}

.selection-readout code {
  color: var(--cyan);
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-weight: 800;
}

@media (max-width: 850px) {
  .intro {
    grid-template-columns: 1fr;
    gap: 0.9rem;
  }

  .eyebrow {
    margin-bottom: 0;
  }

  .workspace {
    grid-template-columns: 1fr;
  }

  textarea {
    min-height: 15rem;
  }

  .form-actions {
    grid-template-columns: 1fr 1fr;
  }

  .graph-stage {
    height: 43rem;
  }
}

@media (max-width: 520px) {
  .lab-header,
  main {
    width: min(100% - 1rem, 1500px);
  }

  .lab-header {
    align-items: flex-start;
  }

  .theme-toggle {
    min-width: 6rem;
  }

  .form-actions {
    grid-template-columns: 1fr;
  }

  .graph-heading {
    align-items: flex-start;
  }

  .graph-stage {
    height: 46rem;
  }
}

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