/* ==========================================================================
   DSA Patterns — stylesheet
   Single source of truth for the whole site. Tokens first, then layout.
   ========================================================================== */

:root {
  --bg:            #0d1117;
  --bg-raised:     #161b22;
  --bg-sunken:     #010409;
  --border:        #262c36;
  --border-strong: #3d444d;

  --fg:            #e6edf3;
  --fg-muted:      #9198a1;
  --fg-faint:      #6b7280;

  --accent:        #58a6ff;
  --accent-dim:    #1f6feb;
  --go:            #00add8;

  --easy:          #3fb950;
  --medium:        #d29922;
  --hard:          #f85149;

  /* Pointer identities, assigned in declaration order by the views. */
  --viz-p0:        #58a6ff;
  --viz-p1:        #d2a8ff;
  --viz-p2:        #3fb950;
  --viz-p3:        #f0883e;
  --viz-p4:        #db61a2;

  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Inter, Roboto, Helvetica, Arial, sans-serif;

  --radius: 8px;
  --maxw: 1100px;
}

@media (prefers-color-scheme: light) {
  :root:not([data-theme="dark"]) {
    --bg:            #ffffff;
    --bg-raised:     #f6f8fa;
    --bg-sunken:     #f0f3f6;
    --border:        #d1d9e0;
    --border-strong: #b7bfc7;

    --fg:            #1f2328;
    --fg-muted:      #59636e;
    --fg-faint:      #818b98;

    --accent:        #0969da;
    --accent-dim:    #0969da;

    --easy:          #1a7f37;
    --medium:        #9a6700;
    --hard:          #cf222e;

    --viz-p0:        #0969da;
    --viz-p1:        #8250df;
    --viz-p2:        #1a7f37;
    --viz-p3:        #bc4c00;
    --viz-p4:        #bf3989;
  }
}

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

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--sans);
  font-size: 15px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

code, pre, kbd { font-family: var(--mono); }

.wrap {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 24px;
}

/* ---------- Header ---------------------------------------------------- */

.site-header {
  border-bottom: 1px solid var(--border);
  background: var(--bg-raised);
  position: sticky;
  top: 0;
  z-index: 20;
}

.site-header .wrap {
  display: flex;
  align-items: center;
  gap: 16px;
  height: 56px;
}

.brand {
  display: flex;
  align-items: baseline;
  gap: 9px;
  font-weight: 650;
  font-size: 15px;
  color: var(--fg);
  letter-spacing: -0.01em;
}
.brand:hover { text-decoration: none; }
.brand .glyph {
  font-family: var(--mono);
  color: var(--go);
  font-size: 17px;
}
.brand .sub {
  color: var(--fg-faint);
  font-weight: 400;
  font-size: 13px;
}

.header-spacer { flex: 1; }

.header-link {
  color: var(--fg-muted);
  font-size: 13.5px;
}

/* ---------- Hero ------------------------------------------------------ */

.hero {
  padding: 56px 0 36px;
  border-bottom: 1px solid var(--border);
}

.hero h1 {
  margin: 0 0 12px;
  font-size: 34px;
  line-height: 1.2;
  letter-spacing: -0.025em;
  font-weight: 700;
}

.hero p {
  margin: 0;
  max-width: 62ch;
  color: var(--fg-muted);
  font-size: 16px;
}

.hero .stats {
  display: flex;
  gap: 28px;
  margin-top: 28px;
  font-size: 13px;
  color: var(--fg-faint);
}
.hero .stats b {
  display: block;
  font-family: var(--mono);
  font-size: 21px;
  font-weight: 600;
  color: var(--fg);
  line-height: 1.3;
}

/* ---------- Controls -------------------------------------------------- */

.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
  margin: 32px 0 22px;
}

#search {
  flex: 1 1 260px;
  min-width: 0;
  background: var(--bg-raised);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--fg);
  padding: 8px 12px;
  font-size: 14px;
  font-family: inherit;
}
#search:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 22%, transparent);
}
#search::placeholder { color: var(--fg-faint); }

.chips { display: flex; flex-wrap: wrap; gap: 6px; }

.chip {
  background: var(--bg-raised);
  border: 1px solid var(--border);
  color: var(--fg-muted);
  border-radius: 999px;
  padding: 5px 13px;
  font-size: 12.5px;
  cursor: pointer;
  font-family: inherit;
  transition: border-color .12s, color .12s;
}
.chip:hover { border-color: var(--border-strong); color: var(--fg); }
.chip[aria-pressed="true"] {
  background: var(--accent-dim);
  border-color: var(--accent-dim);
  color: #fff;
}

/* ---------- Pattern grid ---------------------------------------------- */

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(288px, 1fr));
  gap: 14px;
  padding-bottom: 64px;
}

.card {
  display: flex;
  flex-direction: column;
  background: var(--bg-raised);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
  color: inherit;
  transition: border-color .12s, transform .12s;
}
.card:hover {
  text-decoration: none;
  border-color: var(--border-strong);
  transform: translateY(-1px);
}

.card.stub { opacity: .58; }
.card.stub:hover { transform: none; }

.card-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin-bottom: 8px;
}

.card h3 {
  margin: 0;
  font-size: 15.5px;
  font-weight: 620;
  letter-spacing: -0.01em;
}

.card p {
  margin: 0 0 14px;
  color: var(--fg-muted);
  font-size: 13.5px;
  line-height: 1.55;
  flex: 1;
}

.card-foot {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 12px;
  color: var(--fg-faint);
  font-family: var(--mono);
}

.badge {
  font-family: var(--mono);
  font-size: 10.5px;
  letter-spacing: .04em;
  text-transform: uppercase;
  padding: 2px 7px;
  border-radius: 4px;
  border: 1px solid var(--border-strong);
  color: var(--fg-muted);
  white-space: nowrap;
}
.badge.easy   { color: var(--easy);   border-color: color-mix(in srgb, var(--easy) 45%, transparent); }
.badge.medium { color: var(--medium); border-color: color-mix(in srgb, var(--medium) 45%, transparent); }
.badge.hard   { color: var(--hard);   border-color: color-mix(in srgb, var(--hard) 45%, transparent); }

.section-label {
  font-family: var(--mono);
  font-size: 11.5px;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--fg-faint);
  margin: 40px 0 14px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}

.empty {
  color: var(--fg-faint);
  font-size: 14px;
  padding: 40px 0;
  grid-column: 1 / -1;
}

/* ---------- Pattern page ---------------------------------------------- */

.layout {
  display: grid;
  grid-template-columns: 1fr 216px;
  gap: 48px;
  align-items: start;
  padding: 40px 0 96px;
}

@media (max-width: 860px) {
  .layout { grid-template-columns: 1fr; gap: 0; }
  .toc { display: none; }
}

.toc {
  position: sticky;
  top: 80px;
  font-size: 13px;
  border-left: 1px solid var(--border);
  padding-left: 16px;
}
.toc-title {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--fg-faint);
  margin-bottom: 10px;
}
.toc a {
  display: block;
  color: var(--fg-muted);
  padding: 4px 0;
  line-height: 1.4;
}
.toc a:hover { color: var(--fg); text-decoration: none; }
.toc a.problem { padding-left: 12px; font-size: 12.5px; }

.crumb {
  font-size: 13px;
  color: var(--fg-faint);
  margin-bottom: 18px;
}

.doc h1 {
  margin: 0 0 10px;
  font-size: 31px;
  letter-spacing: -0.025em;
  line-height: 1.2;
}

.tagline {
  margin: 0 0 22px;
  font-size: 17px;
  color: var(--fg-muted);
  max-width: 64ch;
}

.doc h2 {
  margin: 44px 0 14px;
  font-size: 19px;
  letter-spacing: -0.015em;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
  scroll-margin-top: 76px;
}

.doc h3 {
  margin: 32px 0 10px;
  font-size: 16px;
  letter-spacing: -0.01em;
  scroll-margin-top: 76px;
}

.doc p { margin: 0 0 14px; max-width: 72ch; }
.doc ul, .doc ol { margin: 0 0 14px; padding-left: 22px; max-width: 72ch; }
.doc li { margin-bottom: 7px; }

.doc :not(pre) > code {
  background: var(--bg-sunken);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 1px 5px;
  font-size: .875em;
}

.problem-head {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  margin: 36px 0 10px;
  scroll-margin-top: 76px;
}
.problem-head h3 { margin: 0; }

pre {
  background: var(--bg-sunken);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 16px;
  overflow-x: auto;
  font-size: 13px;
  line-height: 1.65;
  margin: 0 0 16px;
  tab-size: 4;
}

.codeblock { position: relative; }
.codeblock .lang {
  position: absolute;
  top: 8px;
  right: 10px;
  font-family: var(--mono);
  font-size: 10.5px;
  color: var(--fg-faint);
  letter-spacing: .05em;
  pointer-events: none;
}

/* Go syntax highlighting */
.tok-kw   { color: #ff7b72; }
.tok-type { color: #79c0ff; }
.tok-fn   { color: #d2a8ff; }
.tok-str  { color: #a5d6ff; }
.tok-num  { color: #79c0ff; }
.tok-com  { color: var(--fg-faint); font-style: italic; }

@media (prefers-color-scheme: light) {
  :root:not([data-theme="dark"]) .tok-kw   { color: #cf222e; }
  :root:not([data-theme="dark"]) .tok-type { color: #0550ae; }
  :root:not([data-theme="dark"]) .tok-fn   { color: #8250df; }
  :root:not([data-theme="dark"]) .tok-str  { color: #0a3069; }
  :root:not([data-theme="dark"]) .tok-num  { color: #0550ae; }
}

/* Callout: recognition cues */
.cues {
  background: var(--bg-raised);
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius);
  padding: 16px 18px;
  margin: 0 0 20px;
}
.cues-title {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 9px;
}
.cues ul { margin: 0; padding-left: 20px; }

.meta-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 13.5px;
  margin: 0 0 16px;
}
.meta-table td, .meta-table th {
  border: 1px solid var(--border);
  padding: 8px 12px;
  text-align: left;
}
.meta-table th {
  background: var(--bg-raised);
  font-weight: 600;
  font-size: 12.5px;
}
.meta-table td:first-child { font-family: var(--mono); white-space: nowrap; }

.complexity {
  display: inline-flex;
  gap: 14px;
  font-family: var(--mono);
  font-size: 12.5px;
  color: var(--fg-muted);
  margin: 0 0 14px;
}

.pager {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-top: 56px;
  padding-top: 22px;
  border-top: 1px solid var(--border);
  font-size: 14px;
}

/* ---------- Visualisation ---------------------------------------------
   Two panes racing on one clock. Everything below is styling for the SVG
   the views mutate; the motion itself comes from transitions on geometry,
   not from JavaScript tweening.
   ---------------------------------------------------------------------- */

.viz {
  margin: 0 0 24px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-raised);
  overflow: hidden;
}
.viz:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.viz-head {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  padding: 11px 14px;
  border-bottom: 1px solid var(--border);
}

.viz-title {
  font-size: 13px;
  font-weight: 600;
  letter-spacing: -0.01em;
  margin-right: auto;
}

.viz-inputs {
  display: flex;
  align-items: center;
  gap: 6px;
  flex-wrap: wrap;
}

.viz-preset {
  font-family: var(--mono);
  font-size: 11px;
  padding: 3px 9px;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--fg-muted);
  cursor: pointer;
  transition: border-color .12s, color .12s;
}
.viz-preset:hover { border-color: var(--border-strong); color: var(--fg); }
.viz-preset[aria-pressed="true"] {
  background: var(--accent-dim);
  border-color: var(--accent-dim);
  color: #fff;
}

.viz-custom {
  font-family: var(--mono);
  font-size: 11.5px;
  padding: 3px 9px;
  width: 190px;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--fg);
}
.viz-custom:focus {
  outline: none;
  border-color: var(--accent);
}
.viz-custom::placeholder { color: var(--fg-faint); }

/* ---- Panes ---- */

.viz-panes {
  display: grid;
  grid-template-columns: 1fr 1fr;
}
.viz-panes.is-single { grid-template-columns: 1fr; }

.viz-pane {
  display: flex;
  flex-direction: column;
  padding: 14px;
  min-width: 0;
}
.viz-pane + .viz-pane { border-left: 1px solid var(--border); }

@media (max-width: 720px) {
  .viz-panes { grid-template-columns: 1fr; }
  .viz-pane + .viz-pane {
    border-left: 0;
    border-top: 1px solid var(--border);
  }
}

.viz-pane-head {
  display: flex;
  align-items: baseline;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 10px;
}

.viz-pane-label {
  font-size: 12.5px;
  font-weight: 600;
}

.viz-cost {
  font-family: var(--mono);
  font-size: 10.5px;
  color: var(--fg-faint);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 1px 5px;
}
.is-best .viz-cost { color: var(--easy); border-color: color-mix(in srgb, var(--easy) 40%, transparent); }

.viz-result {
  margin-left: auto;
  font-family: var(--mono);
  font-size: 11.5px;
  color: var(--easy);
  opacity: 0;
  transition: opacity .25s;
}
.is-done .viz-result { opacity: 1; }

.viz-stage {
  display: flex;
  align-items: flex-end;
  min-height: 132px;
}

.viz-svg {
  width: 100%;
  height: auto;
  display: block;
  font-family: var(--mono);
}

/* ---- Cells ---- */

.viz-box {
  fill: var(--bg);
  stroke: var(--border-strong);
  stroke-width: 1;
  transition: fill .22s, stroke .22s, stroke-width .22s, y .28s, height .28s;
}
.viz-val {
  fill: var(--fg);
  transition: fill .22s, y .28s;
}
.viz-idx { fill: var(--fg-faint); }

.viz-cell { transition: opacity .25s; }

/* Still in play: inside the window, or the un-eliminated search space. */
.viz-cell.is-live .viz-box {
  fill: color-mix(in srgb, var(--accent) 17%, var(--bg));
  stroke: var(--accent);
}

/* Eliminated for good — distinct from merely unvisited. */
.viz-cell.is-dead { opacity: .3; }
.viz-cell.is-dead .viz-box { stroke-dasharray: 2 2; }
.viz-cell.is-dead .viz-val { text-decoration: line-through; }

/* Under comparison this instant. */
.viz-cell.is-cmp .viz-box {
  stroke: var(--medium);
  stroke-width: 2.5;
  fill: color-mix(in srgb, var(--medium) 20%, var(--bg));
}

.viz-cell.is-hit .viz-box {
  stroke: var(--easy);
  stroke-width: 2.5;
  fill: color-mix(in srgb, var(--easy) 26%, var(--bg));
}

/* Predicate strip verdicts. */
.viz-cell.is-true .viz-box  { fill: color-mix(in srgb, var(--easy) 30%, var(--bg)); stroke: var(--easy); }
.viz-cell.is-false .viz-box { fill: color-mix(in srgb, var(--hard) 26%, var(--bg)); stroke: var(--hard); }
.viz-cell.is-unknown .viz-box { fill: var(--bg); stroke: var(--border); stroke-dasharray: 3 3; }

@keyframes viz-write {
  0%   { transform: translateY(-5px); }
  60%  { transform: translateY(1px); }
  100% { transform: translateY(0); }
}
.viz-cell.is-write .viz-val { animation: viz-write .34s ease-out; }

/* ---- Band, span, pointers ---- */

.viz-band {
  fill: color-mix(in srgb, var(--accent) 12%, transparent);
  stroke: color-mix(in srgb, var(--accent) 45%, transparent);
  stroke-width: 1;
  transition: x .3s cubic-bezier(.22,.61,.36,1),
              width .3s cubic-bezier(.22,.61,.36,1),
              y .28s, height .28s, opacity .2s;
}

.viz-span-box {
  fill: color-mix(in srgb, var(--viz-p0) 26%, transparent);
  stroke: var(--viz-p0);
  stroke-width: 1;
  transition: x .3s, width .3s, y .3s, height .3s;
}
.viz-span-text {
  fill: var(--viz-p0);
  font-size: 10.5px;
  font-weight: 600;
  transition: x .3s, y .3s;
}
.viz-span { transition: opacity .2s; }

.viz-ptr {
  transition: transform .3s cubic-bezier(.22,.61,.36,1), opacity .18s;
}
.viz-ptr-chip { fill: var(--viz-p0); }
.viz-ptr-tip  { fill: var(--viz-p0); }
.viz-ptr-text { fill: #fff; font-size: 9.5px; font-weight: 600; }

.viz-ptr-1 .viz-ptr-chip, .viz-ptr-1 .viz-ptr-tip { fill: var(--viz-p1); }
.viz-ptr-2 .viz-ptr-chip, .viz-ptr-2 .viz-ptr-tip { fill: var(--viz-p2); }
.viz-ptr-3 .viz-ptr-chip, .viz-ptr-3 .viz-ptr-tip { fill: var(--viz-p3); }
.viz-ptr-4 .viz-ptr-chip, .viz-ptr-4 .viz-ptr-tip { fill: var(--viz-p4); }

/* Scrubbing should land, not fly. */
.viz-svg.no-anim *, .viz-svg.no-anim { transition: none !important; animation: none !important; }

/* ---- Readouts ---- */

.viz-vars {
  font-family: var(--mono);
  font-size: 11.5px;
  color: var(--fg-muted);
  margin-top: 10px;
  min-height: 17px;
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  align-items: baseline;
}
.viz-vars b { color: var(--fg-faint); font-weight: 400; }
.viz-vars b::after { content: "="; color: var(--fg-faint); }
.viz-vars i { color: var(--border-strong); font-style: normal; }

.viz-caption {
  margin: 7px 0 0;
  font-size: 12.5px;
  line-height: 1.5;
  color: var(--fg-muted);
  min-height: 38px;
  max-width: none;
}
.viz-caption.is-empty::before { content: "\00a0"; }

.viz-meter {
  display: flex;
  align-items: center;
  gap: 9px;
  margin: 10px 0 12px;
}
.viz-meter-track {
  flex: 1;
  height: 5px;
  border-radius: 3px;
  background: var(--bg-sunken);
  border: 1px solid var(--border);
  overflow: hidden;
}
.viz-meter-fill {
  height: 100%;
  width: 0;
  background: var(--hard);
  transition: width .25s ease-out, background .25s;
}
.is-best .viz-meter-fill { background: var(--easy); }

.viz-meter-num {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--fg-muted);
  min-width: 96px;
  text-align: right;
}

/* ---- Code panel ---- */

.viz-code {
  background: var(--bg-sunken);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 8px 0;
  font-family: var(--mono);
  font-size: 11.5px;
  line-height: 1.65;
  max-height: 215px;
  overflow: auto;
  scroll-behavior: smooth;
  tab-size: 2;
}

.viz-line {
  display: flex;
  gap: 10px;
  padding: 0 10px;
  border-left: 2px solid transparent;
  white-space: pre;
  transition: background .15s, border-color .15s;
}
.viz-line .viz-ln {
  color: var(--fg-faint);
  opacity: .5;
  user-select: none;
  min-width: 13px;
  text-align: right;
}
.viz-line code { color: var(--fg-muted); }

.viz-line.is-on {
  background: color-mix(in srgb, var(--accent) 15%, transparent);
  border-left-color: var(--accent);
}
.viz-line.is-on code { color: var(--fg); }
.viz-line.is-on .viz-ln { opacity: 1; color: var(--accent); }

/* ---- Transport ---- */

.viz-controls {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 9px 14px;
  border-top: 1px solid var(--border);
  background: var(--bg-sunken);
}

.viz-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  padding: 0;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: var(--bg-raised);
  color: var(--fg-muted);
  cursor: pointer;
  transition: border-color .12s, color .12s, background .12s;
}
.viz-btn:hover { border-color: var(--border-strong); color: var(--fg); }
.viz-btn svg { width: 15px; height: 15px; fill: currentColor; }
.viz-btn[data-act="toggle"] {
  background: var(--accent-dim);
  border-color: var(--accent-dim);
  color: #fff;
}
.viz-btn[data-act="toggle"]:hover { color: #fff; filter: brightness(1.1); }

.viz-scrub {
  flex: 1;
  min-width: 60px;
  accent-color: var(--accent);
  height: 4px;
  cursor: pointer;
}

.viz-count {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--fg-faint);
  min-width: 60px;
  text-align: right;
}

.viz-speed select {
  font-family: var(--mono);
  font-size: 11px;
  padding: 3px 4px;
  border-radius: 5px;
  border: 1px solid var(--border);
  background: var(--bg-raised);
  color: var(--fg-muted);
  cursor: pointer;
}

.viz-legend {
  padding: 10px 14px;
  border-top: 1px solid var(--border);
  font-size: 12px;
  color: var(--fg-faint);
  line-height: 1.5;
}

.viz-error {
  margin: 0 14px 14px;
  padding: 9px 12px;
  border-radius: 6px;
  border: 1px solid color-mix(in srgb, var(--hard) 45%, transparent);
  background: color-mix(in srgb, var(--hard) 10%, transparent);
  color: var(--hard);
  font-size: 12.5px;
}

/* ---- Linked-list view ---- */

.viz-ll-arrow {
  stroke: var(--border-strong);
  stroke-width: 1.5;
  marker-end: url(#arrowhead);
}
.viz-ll-cycle {
  stroke: var(--hard);
  stroke-dasharray: 4 2;
}
.viz-ll-null {
  stroke: var(--fg-faint);
  stroke-width: 1.5;
  stroke-linecap: round;
}
.viz-ll-dot { fill: var(--border-strong); }
.viz-ll-node.is-visited .viz-box { fill: color-mix(in srgb, var(--fg-faint) 18%, var(--bg)); }

/* ---- Tree view ---- */

.viz-tree-edge {
  stroke: var(--border-strong);
  stroke-width: 1.5;
  transition: stroke .2s;
}
.viz-tree-circle {
  fill: var(--bg-raised);
  stroke: var(--border-strong);
  stroke-width: 1.5;
  transition: fill .22s, stroke .22s, stroke-width .22s;
}
.viz-tree-node.is-visited .viz-tree-circle {
  fill: color-mix(in srgb, var(--fg-faint) 22%, var(--bg));
}
.viz-tree-node.is-live .viz-tree-circle {
  fill: color-mix(in srgb, var(--accent) 28%, var(--bg));
  stroke: var(--accent);
}
.viz-tree-node.is-cmp .viz-tree-circle {
  fill: color-mix(in srgb, var(--medium) 28%, var(--bg));
  stroke: var(--medium);
  stroke-width: 2.5;
}
.viz-tree-node.is-hit .viz-tree-circle {
  fill: color-mix(in srgb, var(--easy) 30%, var(--bg));
  stroke: var(--easy);
  stroke-width: 2.5;
}

/* ---- Graph view ---- */

.viz-graph-edge {
  stroke: var(--border-strong);
  stroke-width: 1.5;
  transition: stroke .2s, stroke-width .2s;
}
.viz-graph-edge.is-active {
  stroke: var(--medium);
  stroke-width: 2.5;
}
.viz-graph-arrow { opacity: .6; }
.viz-graph-node .viz-tree-circle {
  fill: var(--bg-raised);
  stroke: var(--border-strong);
  stroke-width: 1.5;
  transition: fill .22s, stroke .22s, stroke-width .22s;
}
.viz-graph-node.is-visited .viz-tree-circle {
  fill: color-mix(in srgb, var(--fg-faint) 22%, var(--bg));
}
.viz-graph-node.is-live .viz-tree-circle {
  fill: color-mix(in srgb, var(--accent) 28%, var(--bg));
  stroke: var(--accent);
}
.viz-graph-node.is-hit .viz-tree-circle {
  fill: color-mix(in srgb, var(--easy) 30%, var(--bg));
  stroke: var(--easy);
}

/* ---- Grid view ---- */

.viz-grid-cells .viz-box { transition: fill .22s, stroke .22s; }
.viz-grid-cells .viz-cell.is-filled .viz-box {
  fill: color-mix(in srgb, var(--fg-faint) 14%, var(--bg));
}

/* ---- Heap view ---- */

.viz-heap-arr .viz-cell.is-dead { opacity: .3; }

@media (prefers-reduced-motion: reduce) {
  .viz-box, .viz-val, .viz-cell, .viz-band, .viz-ptr,
  .viz-span-box, .viz-span-text, .viz-meter-fill,
  .viz-tree-circle, .viz-tree-edge, .viz-graph-edge { transition: none; }
  .viz-cell.is-write .viz-val { animation: none; }
  .viz-code { scroll-behavior: auto; }
}

/* ---------- Footer ---------------------------------------------------- */

.site-footer {
  border-top: 1px solid var(--border);
  padding: 22px 0;
  color: var(--fg-faint);
  font-size: 12.5px;
}
.site-footer .wrap {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}