/* ── Reset & Base ── */
*, *::before, *::after { margin:0; padding:0; box-sizing:border-box; }
:root {
  --bg:       #0b0e17;
  --surface:  #141825;
  --surface2: #1c2133;
  --border:   #2a3050;
  --text:     #e2e6f0;
  --muted:    #7a82a0;
  --accent:   #6c5ce7;
  --accent2:  #a29bfe;
  --search:   #3b82f6;          /* blue */
  --search-bg:rgba(59,130,246,.18);
  --look:     #22c55e;          /* green */
  --look-bg:  rgba(34,197,94,.18);
  --match:    #f97316;          /* orange */
  --match-bg: rgba(249,115,22,.18);
  --danger:   #ef4444;
  --radius:   12px;
  --font:     'Inter', system-ui, sans-serif;
  --mono:     'JetBrains Mono', 'Fira Code', monospace;
  --header-h: 56px;
}
html { font-size:16px; }
body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  line-height: 1.45;
  min-height: 100dvh;
  padding-top: calc(var(--header-h) + 12px);
  -webkit-tap-highlight-color: transparent;
}

/* ── Header ── */
#top-header {
  position: fixed; top:0; left:0; right:0; z-index:100;
  height: var(--header-h);
  display: flex; align-items: center; gap:12px;
  padding: 0 16px;
  background: rgba(11,14,23,.88);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border);
}
#btn-back {
  display:inline-flex; align-items:center; gap:4px;
  background:none; border:none; color:var(--accent2);
  font: 600 .9rem var(--font); cursor:pointer;
  padding:6px 10px; border-radius:8px;
  transition: background .2s;
}
#btn-back:hover { background:rgba(108,92,231,.15); }
#header-title {
  flex:1; text-align:center;
  font-size:1.05rem; font-weight:700;
  letter-spacing:.02em;
  background: linear-gradient(135deg, var(--accent2), var(--search));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}
.header-spacer { width:68px; }

/* ── Main ── */
#app { max-width:740px; margin:0 auto; padding:0 14px 40px; }

/* ── Stats Bar ── */
#stats-bar {
  display:flex; gap:10px; margin-bottom:18px;
}
.stat-card {
  flex:1; text-align:center;
  background: var(--surface);
  border:1px solid var(--border);
  border-radius: var(--radius);
  padding:12px 8px;
  transition: transform .2s, box-shadow .2s;
}
.stat-card:hover { transform:translateY(-2px); box-shadow:0 4px 18px rgba(0,0,0,.35); }
.stat-card.accent { border-color: var(--accent); }
.stat-label { display:block; font-size:.72rem; text-transform:uppercase; letter-spacing:.08em; color:var(--muted); margin-bottom:4px; }
.stat-value { font:700 1.35rem var(--mono); }
.stat-value small { font-size:.7rem; font-weight:500; color:var(--muted); }

/* ── Input ── */
#input-section { margin-bottom:16px; }
.input-row { display:flex; align-items:center; gap:10px; flex-wrap:wrap; margin-bottom:8px; }
.input-label { font-weight:600; font-size:.88rem; white-space:nowrap; }
.preset-chips { display:flex; gap:6px; flex-wrap:wrap; }
.chip {
  font: 600 .72rem var(--mono);
  padding:5px 10px; border-radius:20px;
  background: var(--surface2); border:1px solid var(--border);
  color:var(--accent2); cursor:pointer;
  transition: background .2s, border-color .2s;
}
.chip:hover, .chip.active { background:var(--accent); border-color:var(--accent); color:#fff; }
#input-text {
  width:100%; font: 500 1rem var(--mono);
  padding:12px 14px; border-radius:var(--radius);
  background:var(--surface); border:1px solid var(--border);
  color:var(--text); outline:none;
  transition: border-color .2s;
}
#input-text:focus { border-color:var(--accent); }

/* ── Sliders ── */
#sliders-section { display:flex; gap:16px; margin-bottom:18px; }
.slider-group { flex:1; }
.slider-group label {
  display:flex; align-items:center; gap:6px;
  font-size:.82rem; font-weight:600; margin-bottom:6px;
}
.slider-val {
  font: 700 .82rem var(--mono);
  color:var(--accent2);
  background:var(--surface2);
  padding:2px 7px; border-radius:6px;
}
input[type=range] {
  -webkit-appearance:none; width:100%; height:48px;
  background:transparent; cursor:pointer;
}
input[type=range]::-webkit-slider-runnable-track {
  height:8px; border-radius:4px;
  background: linear-gradient(90deg, var(--accent), var(--search));
}
input[type=range]::-webkit-slider-thumb {
  -webkit-appearance:none; width:28px; height:28px;
  border-radius:50%; background:#fff;
  box-shadow:0 2px 8px rgba(0,0,0,.4);
  margin-top:-10px;
}
input[type=range]::-moz-range-track {
  height:8px; border-radius:4px;
  background: linear-gradient(90deg, var(--accent), var(--search));
}
input[type=range]::-moz-range-thumb {
  width:28px; height:28px; border:none;
  border-radius:50%; background:#fff;
  box-shadow:0 2px 8px rgba(0,0,0,.4);
}

/* ── Controls ── */
#controls-section {
  display:flex; gap:10px; margin-bottom:20px; justify-content:center;
}
.ctrl-btn {
  display:inline-flex; align-items:center; gap:6px;
  font: 600 .88rem var(--font);
  padding:10px 18px; border-radius:10px;
  border:1px solid var(--border); background:var(--surface);
  color:var(--text); cursor:pointer;
  transition: background .2s, transform .15s, border-color .2s;
}
.ctrl-btn:hover { background:var(--surface2); transform:translateY(-1px); }
.ctrl-btn.primary { background:var(--accent); border-color:var(--accent); color:#fff; }
.ctrl-btn.primary:hover { background:#5b4bd6; }

/* ── Visualization ── */
#viz-section { margin-bottom:22px; }
#legend { display:flex; gap:16px; justify-content:center; margin-bottom:10px; flex-wrap:wrap; }
.legend-item { display:flex; align-items:center; gap:5px; font-size:.76rem; font-weight:600; color:var(--muted); }
.legend-swatch { width:14px; height:14px; border-radius:4px; }
.search-legend .legend-swatch { background: var(--search-bg); border:2px solid var(--search); }
.lookahead-legend .legend-swatch { background: var(--look-bg); border:2px solid var(--look); }
.match-legend .legend-swatch { background: var(--match-bg); border:2px solid var(--match); }

#viz-container {
  position:relative;
  background: var(--surface);
  border:1px solid var(--border);
  border-radius: var(--radius);
  padding:40px 14px 18px;
  overflow-x:auto;
  min-height:88px;
}
#arrow-svg {
  position:absolute; top:0; left:0;
  width:100%; height:100%;
  pointer-events:none;
  overflow:visible;
}
#char-strip {
  display: flex;
  flex-wrap: wrap;
  gap: 2px;
  justify-content: center;
}
.char-cell {
  display:inline-flex; align-items:center; justify-content:center;
  width:30px; height:38px;
  font: 700 1.1rem var(--mono);
  border-radius:6px; position:relative;
  transition: background .25s, color .25s, transform .25s;
  flex-shrink:0;
}
.char-cell.search-buf { background:var(--search-bg); color:var(--search); }
.char-cell.look-buf   { background:var(--look-bg);   color:var(--look);   }
.char-cell.matched     { background:var(--match-bg);  color:var(--match); transform:scale(1.08); }
.char-cell.processed   { opacity:.35; }

#step-info {
  margin-top:10px; text-align:center;
  font: 500 .82rem var(--mono);
  color: var(--muted);
  min-height: 20px;
}

/* ── Output Tokens ── */
#output-section h2 {
  font-size:.88rem; font-weight:700; margin-bottom:8px;
  color:var(--muted); text-transform:uppercase; letter-spacing:.06em;
}
#token-list { display:flex; flex-wrap:wrap; gap:8px; }
.token-card {
  background:var(--surface); border:1px solid var(--border);
  border-radius:10px; padding:8px 12px;
  font: 600 .8rem var(--mono);
  transition: opacity .3s, transform .3s;
  animation: tokenIn .35s ease-out;
}
.token-card .tok-offset  { color:var(--search); }
.token-card .tok-length  { color:var(--match);  }
.token-card .tok-char    { color:var(--look);   }
@keyframes tokenIn {
  from { opacity:0; transform:translateY(8px) scale(.92); }
  to   { opacity:1; transform:translateY(0) scale(1); }
}

/* ── Error toast ── */
.error-toast {
  position:fixed; bottom:20px; left:50%; transform:translateX(-50%);
  background:var(--danger); color:#fff;
  font: 600 .85rem var(--font);
  padding:10px 20px; border-radius:10px;
  z-index:200; animation: toastIn .3s ease-out;
  box-shadow: 0 6px 24px rgba(239,68,68,.4);
}
@keyframes toastIn {
  from { opacity:0; transform:translate(-50%,12px); }
  to   { opacity:1; transform:translate(-50%,0);   }
}

/* ── Responsive ── */
@media (max-width:560px) {
  :root { --header-h:48px; }
  #header-title { font-size:.88rem; }
  #sliders-section { flex-direction:column; gap:10px; }
  .stat-value { font-size:1.1rem; }
  .char-cell { width:24px; height:32px; font-size:.92rem; }
  #controls-section { flex-wrap:wrap; }
  .ctrl-btn { flex:1; justify-content:center; padding:10px 10px; }
  #viz-container { padding:36px 8px 14px; }
}