/* Data Structure Visualizer — self-contained styles, palette mirrors LK Forge. */
:root {
  --dv-bg: #f5f7ff; --dv-surface: #ffffff; --dv-surface2: #eef1fb;
  --dv-text: #0b1020; --dv-muted: #5a6178; --dv-accent: #0e7490;
  --dv-border: #dde2f2; --dv-green: #16a34a; --dv-amber: #d97706;
  --dv-red: #dc2626; --dv-node: #6366f1;
  --dv-display: 'Orbitron', system-ui, sans-serif;
  --dv-body: 'Outfit', system-ui, -apple-system, sans-serif;
}
@media (prefers-color-scheme: dark) {
  :root {
    --dv-bg: #0b1020; --dv-surface: #151b30; --dv-surface2: #1b2340;
    --dv-text: #eef1fb; --dv-muted: #9aa3c0; --dv-accent: #22d3ee;
    --dv-border: #2a3358; --dv-green: #4ade80; --dv-amber: #fbbf24;
    --dv-red: #f87171; --dv-node: #818cf8;
  }
}
* { box-sizing: border-box; }
.dv-body { margin: 0; background: var(--dv-bg); color: var(--dv-text); font-family: var(--dv-body); line-height: 1.6; }
.dv-wrap { max-width: 900px; margin: 0 auto; padding: 1.25rem; }

.dv-header { display: flex; align-items: center; justify-content: space-between; padding: 1rem 1.25rem; border-bottom: 1px solid var(--dv-border); background: var(--dv-surface); }
.dv-logo { font-family: var(--dv-display); font-weight: 900; color: var(--dv-text); text-decoration: none; }
.dv-logo span { color: var(--dv-accent); }
.dv-nav a { color: var(--dv-muted); text-decoration: none; margin-left: 1.1rem; font-weight: 600; font-size: 0.9rem; }
.dv-nav a:hover { color: var(--dv-accent); }

.dv-eyebrow { font-size: 0.72rem; font-weight: 700; letter-spacing: 0.08em; text-transform: uppercase; color: var(--dv-accent); }
h1.dv-h1 { font-family: var(--dv-display); font-size: clamp(1.6rem, 4.5vw, 2.6rem); font-weight: 900; line-height: 1.12; margin: 0.4rem 0 0.75rem; }
.dv-lead { color: var(--dv-muted); font-size: 1.02rem; margin: 0 0 1.5rem; }

.dv-controls { display: flex; flex-wrap: wrap; gap: 1rem 1.25rem; align-items: flex-end; margin-bottom: 1rem; }
.dv-group { display: flex; flex-direction: column; gap: 0.35rem; }
.dv-group-label { font-size: 0.68rem; font-weight: 700; letter-spacing: 0.06em; text-transform: uppercase; color: var(--dv-muted); }
.dv-select, .dv-input { font-family: var(--dv-body); font-weight: 700; font-size: 0.85rem; color: var(--dv-text); background: var(--dv-surface); border: 1px solid var(--dv-border); border-radius: 8px; padding: 0.5rem 0.7rem; }
.dv-select { min-width: 190px; }
.dv-input { width: 90px; }
.dv-btnrow { display: flex; gap: 0.4rem; flex-wrap: wrap; }
.dv-btn { font-family: var(--dv-body); font-weight: 700; font-size: 0.85rem; cursor: pointer; background: var(--dv-surface); color: var(--dv-muted); border: 1px solid var(--dv-border); border-radius: 8px; padding: 0.5rem 0.95rem; }
.dv-btn:hover:not(:disabled) { border-color: var(--dv-accent); color: var(--dv-text); }
.dv-btn:disabled { opacity: 0.5; cursor: not-allowed; }
.dv-btn.primary { background: var(--dv-accent); color: #fff; border-color: var(--dv-accent); }
.dv-btn:focus-visible, a:focus-visible, .dv-select:focus-visible, .dv-input:focus-visible { outline: 2px solid var(--dv-accent); outline-offset: 2px; }
@media (prefers-color-scheme: dark) { .dv-btn.primary { color: var(--dv-bg); } }

.dv-stage { background: var(--dv-surface2); border: 1px solid var(--dv-border); border-radius: 12px; padding: 1rem; min-height: 320px; display: flex; align-items: center; justify-content: center; overflow: auto; }

/* Stack: vertical, top of stack at the top */
.dv-stack { display: flex; flex-direction: column-reverse; gap: 6px; align-items: center; }
.dv-stack-wrap { display: flex; flex-direction: column; align-items: center; gap: 0.4rem; }
/* Queue: horizontal, front at the left */
.dv-queue { display: flex; flex-direction: row; gap: 6px; align-items: center; flex-wrap: wrap; }
.dv-cell { min-width: 54px; height: 46px; display: flex; align-items: center; justify-content: center; background: var(--dv-node); color: #fff; font-family: var(--dv-display); font-weight: 700; border-radius: 8px; padding: 0 0.6rem; transition: transform .18s ease, background .18s ease; }
.dv-cell.hot { background: var(--dv-amber); transform: scale(1.08); }
.dv-cell.out { background: var(--dv-red); }
.dv-caplabel { font-size: 0.7rem; font-weight: 700; letter-spacing: .05em; text-transform: uppercase; color: var(--dv-muted); }
.dv-empty { color: var(--dv-muted); font-size: 0.95rem; }

/* BST */
.dv-tree { width: 100%; height: auto; }
.dv-tree .edge { stroke: var(--dv-border); stroke-width: 2; }
.dv-tree .node circle { fill: var(--dv-node); transition: fill .18s ease; }
.dv-tree .node.hot circle { fill: var(--dv-amber); }
.dv-tree .node.found circle { fill: var(--dv-green); }
.dv-tree .node.new circle { fill: var(--dv-green); }
.dv-tree .node text { fill: #fff; font-family: var(--dv-display); font-weight: 700; font-size: 14px; text-anchor: middle; dominant-baseline: central; }

.dv-status { margin-top: 1rem; background: var(--dv-surface2); border: 1px solid var(--dv-border); border-radius: 8px; padding: 0.7rem 0.9rem; color: var(--dv-text); font-size: 0.9rem; min-height: 1.4em; }

.dv-section { margin-top: 2.5rem; }
.dv-section h2 { font-family: var(--dv-display); font-weight: 900; font-size: 1.3rem; margin: 0 0 0.75rem; }
.dv-section p { color: var(--dv-muted); }
.dv-section a { color: var(--dv-accent); text-decoration: none; font-weight: 600; }
.dv-section ul { color: var(--dv-muted); padding-left: 1.15rem; }
.dv-section li { margin-bottom: 0.5rem; }
.dv-faq h3 { font-family: var(--dv-body); font-weight: 700; font-size: 1.02rem; color: var(--dv-text); margin: 1.15rem 0 0.3rem; }
.dv-foot { border-top: 1px solid var(--dv-border); margin-top: 3rem; padding: 1.5rem 1.25rem; text-align: center; color: var(--dv-muted); font-size: 0.85rem; }
.dv-foot a { color: var(--dv-accent); text-decoration: none; }

/* print layout — hide chrome + interactive controls, keep visualization & content */
@media print {
  .dv-header, .dv-foot, .dv-controls, .dv-status { display: none !important; }
  body { background: #fff !important; color: #000 !important; }
  @page { margin: 1.5cm; }
}