/* ============================================================
   HuffZip — visual system (light, schematic)
   Flat technical panels, hairline rules, sharp corners.
   Two signals carry meaning: teal = bit 0, amber = bit 1.
   ============================================================ */

:root {
  --bg:        #eaefed;
  --panel:     #f6f9f8;
  --field:     #ffffff;
  --raised:    #e0e8e6;
  --line:      #b9cbc7;   /* visible hairline */
  --line-soft: #cfdbd8;
  --ink:       #0c2226;
  --ink-dim:   #35504f;
  --muted:     #647a77;

  --zero:  #0c9284; /* bit 0 */
  --one:   #b3720c; /* bit 1 */
  --zero-soft: rgba(12, 146, 132, 0.12);
  --one-soft:  rgba(179, 114, 12, 0.12);

  --danger: #bf4e33;

  --display: 'Space Grotesk', 'Segoe UI', system-ui, sans-serif;
  --body:    'IBM Plex Sans', system-ui, sans-serif;
  --mono:    'IBM Plex Mono', ui-monospace, 'SF Mono', Menlo, monospace;

  --maxw: 1120px;
  --ease: cubic-bezier(0.22, 1, 0.36, 1);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--body);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 28px; }

h1, h2, h3 {
  font-family: var(--display);
  font-weight: 600;
  line-height: 1.06;
  letter-spacing: -0.02em;
  margin: 0;
}

.eyebrow {
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.26em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0 0 14px;
}
.eyebrow::before { content: '// '; color: var(--zero); }

a { color: inherit; }

/* ============================================================
   Top bar
   ============================================================ */

.topbar {
  position: sticky;
  top: 0;
  z-index: 40;
  background: rgba(234, 239, 237, 0.9);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}
.topbar-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 62px;
}

.brand { display: flex; align-items: center; gap: 11px; text-decoration: none; color: var(--ink); }
.brand-mark { width: 30px; height: 30px; display: block; }
.brand-name { font-family: var(--display); font-weight: 700; font-size: 1.16rem; letter-spacing: -0.01em; }
.brand-name b { color: var(--one); font-weight: 700; }

.topbar-actions { display: flex; align-items: center; gap: 6px; }

.lang-toggle { display: inline-flex; border: 1px solid var(--line); font-family: var(--mono); font-size: 0.76rem; }
.lang-toggle button {
  appearance: none; border: 0; background: transparent; color: var(--muted);
  padding: 6px 12px; cursor: pointer; transition: color 0.15s, background 0.15s;
}
.lang-toggle button + button { border-left: 1px solid var(--line); }
.lang-toggle button[aria-pressed='true'] { background: var(--ink); color: #fff; }
.lang-toggle button:focus-visible { outline: 2px solid var(--zero); outline-offset: -2px; }

.ghost-link {
  font-family: var(--mono); font-size: 0.78rem; color: var(--muted);
  text-decoration: none; padding: 6px 4px; border-bottom: 1px solid transparent;
  transition: color 0.15s, border-color 0.15s;
}
.ghost-link:hover { color: var(--ink); border-color: var(--zero); }

/* ============================================================
   Hero
   ============================================================ */

.hero { padding: 64px 0 30px; }
.hero-head { max-width: 920px; margin-bottom: 36px; }
.hero h1 { font-size: clamp(2.5rem, 6vw, 4.1rem); margin-bottom: 18px; }
.hero h1 .accent { color: var(--zero); }
.hero-lede { font-size: 1.1rem; color: var(--ink-dim); max-width: 58ch; }

.studio { display: grid; grid-template-columns: 1.05fr 0.95fr; border: 1px solid var(--line); }
.studio > .panel + .panel { border-left: 1px solid var(--line); }

/* Flat bordered panel with schematic corner ticks — no shadow, no radius. */
.panel { position: relative; background: var(--panel); }
.panel::before, .panel::after {
  content: ''; position: absolute; width: 9px; height: 9px; pointer-events: none;
}
.panel::before { top: 6px; left: 6px; border-top: 2px solid var(--zero); border-left: 2px solid var(--zero); }
.panel::after { bottom: 6px; right: 6px; border-bottom: 2px solid var(--zero); border-right: 2px solid var(--zero); }

.panel-head {
  display: flex; align-items: center; justify-content: space-between;
  padding: 15px 20px; border-bottom: 1px solid var(--line);
}
.panel-title {
  font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.18em;
  text-transform: uppercase; color: var(--muted);
}
.panel-body { padding: 20px; }

/* input */
.editor {
  width: 100%; min-height: 244px; resize: vertical;
  background: var(--field); border: 1px solid var(--line);
  color: var(--ink); font-family: var(--mono); font-size: 0.95rem;
  line-height: 1.7; padding: 15px 16px; transition: border-color 0.15s, box-shadow 0.15s;
}
.editor:focus { outline: none; border-color: var(--zero); box-shadow: inset 0 0 0 1px var(--zero); }

.editor-foot { display: flex; align-items: center; justify-content: space-between; margin-top: 14px; gap: 12px; }
.count { font-family: var(--mono); font-size: 0.78rem; color: var(--muted); }
.count b { color: var(--ink); font-weight: 500; }

.samples { display: flex; gap: 6px; flex-wrap: wrap; }
.chip {
  appearance: none; border: 1px solid var(--line); background: transparent;
  color: var(--ink-dim); font-family: var(--mono); font-size: 0.73rem;
  padding: 5px 10px; cursor: pointer; transition: border-color 0.15s, color 0.15s, background 0.15s;
}
.chip:hover { border-color: var(--zero); color: var(--ink); background: var(--zero-soft); }
.chip:focus-visible { outline: 2px solid var(--zero); outline-offset: 1px; }

.editor.dragging { border-color: var(--zero); box-shadow: inset 0 0 0 2px var(--zero); background: var(--zero-soft); }

.io-row { display: flex; align-items: center; gap: 12px; margin-top: 12px; flex-wrap: wrap; }
.btn-file {
  display: inline-flex; align-items: center; gap: 7px;
  border: 1px solid var(--ink); background: var(--ink); color: #fff;
  font-family: var(--mono); font-size: 0.74rem; padding: 7px 13px; cursor: pointer;
  transition: background 0.15s, color 0.15s;
}
.btn-file::before { content: '↥'; font-size: 0.9rem; line-height: 1; }
.btn-file:hover { background: var(--zero); border-color: var(--zero); }
.btn-file:focus-within { outline: 2px solid var(--zero); outline-offset: 2px; }
.io-hint { font-family: var(--mono); font-size: 0.74rem; color: var(--muted); }
.io-hint.io-err { color: var(--danger); }

/* gauge */
.gauge { display: flex; flex-direction: column; gap: 20px; }
.ratio-readout { display: flex; align-items: baseline; gap: 10px; }
.ratio-big {
  font-family: var(--display); font-weight: 700; font-size: clamp(2.6rem, 7vw, 3.6rem);
  letter-spacing: -0.03em; color: var(--one); font-variant-numeric: tabular-nums; line-height: 1;
}
.ratio-label { font-size: 0.9rem; color: var(--muted); }

.bars { display: flex; flex-direction: column; gap: 10px; }
.bar-row { display: grid; grid-template-columns: 78px 1fr; align-items: center; gap: 12px; }
.bar-tag { font-family: var(--mono); font-size: 0.7rem; letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); }
.bar-track { position: relative; height: 24px; background: var(--raised); border: 1px solid var(--line-soft); overflow: hidden; }
.bar-fill { position: absolute; inset: 0 auto 0 0; width: 0; transition: width 0.5s var(--ease); }
.bar-fill.orig { background: repeating-linear-gradient(45deg, #c1d1ce, #c1d1ce 6px, #b6c8c4 6px, #b6c8c4 12px); width: 100%; }
.bar-fill.comp { background: var(--one); }
.bar-val { position: absolute; right: 8px; top: 50%; transform: translateY(-50%); font-family: var(--mono); font-size: 0.72rem; color: var(--ink); z-index: 2; }

.metrics { display: grid; grid-template-columns: 1fr 1fr; gap: 1px; background: var(--line); border: 1px solid var(--line); }
.metric { background: var(--panel); padding: 13px 15px; }
.metric-k { font-family: var(--mono); font-size: 0.66rem; letter-spacing: 0.1em; text-transform: uppercase; color: var(--muted); margin-bottom: 5px; }
.metric-v { font-family: var(--display); font-weight: 500; font-size: 1.26rem; font-variant-numeric: tabular-nums; }
.metric-v small { font-size: 0.72rem; color: var(--muted); font-family: var(--mono); font-weight: 400; }

.verify { display: inline-flex; align-items: center; gap: 8px; font-family: var(--mono); font-size: 0.76rem; color: var(--zero); }
.verify .dot { width: 7px; height: 7px; background: var(--zero); }
.verify.bad { color: var(--danger); }
.verify.bad .dot { background: var(--danger); }

/* ============================================================
   Sections
   ============================================================ */

.section { padding: 62px 0; border-top: 1px solid var(--line); }
.section-head { max-width: 640px; margin-bottom: 32px; }
.section-head h2 { font-size: clamp(1.7rem, 4vw, 2.35rem); margin-bottom: 12px; }
.section-head p { color: var(--ink-dim); margin: 0; }

/* tree (signature) */
.tree-panel { border: 1px solid var(--line); background: var(--panel); }
.tree-scroll { overflow: auto; padding: 10px; }
#tree-svg { display: block; margin: 0 auto; }

.edge { stroke: var(--line); stroke-width: 1.5; fill: none; }
.edge.b0 { stroke: var(--zero); }
.edge.b1 { stroke: var(--one); }
.edge-label { font-family: var(--mono); font-size: 11px; font-weight: 500; }
.edge-label.b0 { fill: var(--zero); }
.edge-label.b1 { fill: var(--one); }

.node-internal { fill: var(--ink); }
.node-leaf { fill: var(--field); stroke: var(--ink); stroke-width: 1.4; }
.node-sym { font-family: var(--mono); font-size: 13px; fill: var(--ink); font-weight: 500; }
.node-freq { font-family: var(--mono); font-size: 10px; fill: var(--muted); }

.tree-legend { display: flex; gap: 22px; padding: 13px 20px; border-top: 1px solid var(--line); flex-wrap: wrap; }
.legend-item { display: inline-flex; align-items: center; gap: 8px; font-family: var(--mono); font-size: 0.76rem; color: var(--muted); }
.legend-swatch { width: 22px; height: 3px; }
.legend-swatch.b0 { background: var(--zero); }
.legend-swatch.b1 { background: var(--one); }

/* code table */
.code-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(188px, 1fr)); gap: 0; }
.code-card {
  display: flex; align-items: center; justify-content: space-between; gap: 12px;
  background: var(--panel); border: 1px solid var(--line); margin: 0 -1px -1px 0;
  padding: 11px 14px;
}
.code-sym { font-family: var(--mono); font-size: 0.95rem; color: var(--ink); display: flex; align-items: baseline; gap: 9px; }
.code-sym .freq { font-size: 0.7rem; color: var(--muted); }
.code-bits { font-family: var(--mono); font-size: 0.9rem; letter-spacing: 0.04em; }
.code-bits .z { color: var(--zero); }
.code-bits .o { color: var(--one); }

/* bitstream */
.stream-panel { border: 1px solid var(--line); background: var(--panel); }
.stream-body { padding: 18px 20px; }
.stream { font-family: var(--mono); font-size: 0.85rem; line-height: 2.1; max-height: 200px; overflow: auto; }
.stream .byte { display: inline-block; margin: 0 4px 2px 0; }
.stream .byte .z { color: var(--zero); }
.stream .byte .o { color: var(--one); }
.stream-more { color: var(--muted); font-style: italic; }

/* how it works — a real sequence, so the numbering carries meaning */
.steps { display: grid; grid-template-columns: repeat(4, 1fr); gap: 0; border: 1px solid var(--line); }
.step { position: relative; padding: 22px 20px; border-left: 1px solid var(--line); }
.step:first-child { border-left: 0; }
.step-n { font-family: var(--mono); font-size: 0.76rem; color: var(--one); display: block; margin-bottom: 12px; }
.step h3 { font-size: 1.04rem; margin: 0 0 8px; }
.step p { color: var(--ink-dim); font-size: 0.92rem; margin: 0; }

/* about / engine */
.about-grid { display: grid; grid-template-columns: 1.2fr 0.8fr; gap: 44px; align-items: start; }
.about-grid p { color: var(--ink-dim); }
.about-grid p + p { margin-top: 14px; }
.facts { border: 1px solid var(--line); background: var(--panel); }
.fact { display: flex; justify-content: space-between; gap: 16px; padding: 13px 16px; border-bottom: 1px solid var(--line); font-size: 0.9rem; }
.fact:last-child { border-bottom: 0; }
.fact-k { color: var(--muted); font-family: var(--mono); font-size: 0.78rem; }
.fact-v { color: var(--ink); text-align: right; }

/* footer */
.foot { border-top: 1px solid var(--line); padding: 34px 0 46px; }
.foot-inner { display: flex; justify-content: space-between; align-items: center; gap: 20px; flex-wrap: wrap; }
.foot p { margin: 0; color: var(--muted); font-size: 0.85rem; }
.foot .mono { font-family: var(--mono); }
.foot-links { display: inline-flex; align-items: center; gap: 10px; }
.foot-links a { color: var(--ink-dim); text-decoration: none; border-bottom: 1px solid var(--line); }
.foot-links a:hover { color: var(--ink); border-color: var(--zero); }
.foot-sep { color: var(--muted); }

/* ============================================================
   Legal page
   ============================================================ */
.legal { padding: 56px 0 72px; }
.legal-inner { max-width: 760px; }
.legal h1 { font-size: clamp(2rem, 5vw, 3rem); margin-bottom: 10px; }
.legal .lead { color: var(--ink-dim); margin: 0 0 8px; }
.legal .updated { font-family: var(--mono); font-size: 0.76rem; color: var(--muted); margin: 0; }
.legal section { border-top: 1px solid var(--line); padding-top: 22px; margin-top: 30px; }
.legal h2 { font-size: 1.18rem; margin-bottom: 12px; }
.legal h2::before { content: '// '; color: var(--zero); font-family: var(--mono); font-size: 0.8em; }
.legal p { color: var(--ink-dim); margin: 0 0 10px; }
.legal address { font-style: normal; color: var(--ink-dim); font-family: var(--mono); font-size: 0.86rem; line-height: 1.9; }
.legal a { color: var(--zero); text-decoration: none; border-bottom: 1px solid var(--line-soft); }
.legal a:hover { border-color: var(--zero); }

/* responsive */
@media (max-width: 920px) {
  .studio { grid-template-columns: 1fr; }
  .studio > .panel + .panel { border-left: 0; border-top: 1px solid var(--line); }
  .about-grid { grid-template-columns: 1fr; gap: 28px; }
  .steps { grid-template-columns: 1fr 1fr; }
  .step:nth-child(-n+2) { border-top: 0; }
  .step:nth-child(2n+1) { border-left: 0; }
  .step:nth-child(n+3) { border-top: 1px solid var(--line); }
}
@media (max-width: 560px) {
  .wrap { padding: 0 18px; }
  .hero { padding: 46px 0 22px; }
  .steps { grid-template-columns: 1fr; }
  .step { border-left: 0; border-top: 1px solid var(--line); }
  .step:first-child { border-top: 0; }
  .metrics { grid-template-columns: 1fr; }
  .ghost-link.hide-sm { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; scroll-behavior: auto !important; }
}