*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg:              #f4f5f7;
  --surface:         #ffffff;
  --surface-2:       #f0f1f4;
  --border:          #e2e4e9;
  --accent:          #4f46e5;
  --accent-hover:    #4338ca;
  --accent-light:    #eef2ff;
  --accent-mid:      #818cf8;
  --text-primary:    #111827;
  --text-secondary:  #6b7280;
  --text-tertiary:   #9ca3af;
  --token-flash-bg:  #fef9c3;
  --token-flash-fg:  #854d0e;
  --token-recent-bg: #ede9fe;
  --success:         #16a34a;
  --radius:          10px;
  --radius-sm:       6px;
  --shadow-sm:       0 1px 2px rgba(0,0,0,.06), 0 1px 3px rgba(0,0,0,.08);
  --shadow:          0 2px 8px rgba(0,0,0,.08), 0 1px 3px rgba(0,0,0,.05);
  --font:            'Inter', system-ui, sans-serif;
  --font-mono:       'JetBrains Mono', 'Fira Code', monospace;
}

html { height: 100%; }
body {
  height: 100%;
  display: flex;
  flex-direction: column;
  background: var(--bg);
  color: var(--text-primary);
  font-family: var(--font);
  font-size: 14px;
  line-height: 1.5;
}

/* ── HEADER ─────────────────────────────────────────── */
header {
  display: flex;
  align-items: baseline;
  gap: 12px;
  padding: 16px 24px 12px;
  border-bottom: 1px solid var(--border);
  background: var(--surface);
}
header h1 {
  font-size: 1.05rem;
  font-weight: 700;
  letter-spacing: -.01em;
  color: var(--text-primary);
}
header span.sub {
  font-size: .8rem;
  color: var(--text-secondary);
  font-weight: 400;
}

/* ── MAIN GRID ──────────────────────────────────────── */
main {
  display: grid;
  grid-template-columns: 400px 1fr;
  gap: 16px;
  padding: 16px;
  flex: 1;
  min-height: 0;
}

/* ── CARDS ──────────────────────────────────────────── */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  padding: 16px;
}
.card-title {
  font-size: .7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .07em;
  color: var(--text-tertiary);
  margin-bottom: 10px;
}

/* ── LEFT PANEL ─────────────────────────────────────── */
.panel-left {
  display: flex;
  flex-direction: column;
  gap: 12px;
  overflow-y: auto;
}

/* corpus section */
.corpus-textarea {
  width: 100%;
  height: 130px;
  resize: vertical;
  font-family: var(--font-mono);
  font-size: .75rem;
  line-height: 1.5;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 8px 10px;
  color: var(--text-secondary);
  background: var(--surface-2);
  outline: none;
  transition: border-color .15s;
}
.corpus-textarea:focus { border-color: var(--accent-mid); background: #fff; }

.build-row {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-top: 8px;
}
.model-stats {
  font-size: .75rem;
  color: var(--text-secondary);
  flex: 1;
  min-height: 16px;
}
.model-stats span { color: var(--accent); font-weight: 500; }

/* segmented control */
.seg-label {
  font-size: .75rem;
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: 6px;
}
.seg-control {
  display: flex;
  gap: 3px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 3px;
}
.seg-control input[type=radio] { display: none; }
.seg-control label {
  flex: 1;
  text-align: center;
  padding: 5px 0;
  border-radius: 4px;
  cursor: pointer;
  font-size: .8rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: background .15s, color .15s, box-shadow .15s;
  user-select: none;
}
.seg-control input:checked + label {
  background: var(--surface);
  color: var(--accent);
  box-shadow: var(--shadow-sm);
}

/* prompt */
.prompt-row {
  display: flex;
  gap: 8px;
  align-items: stretch;
}
.prompt-input {
  flex: 1;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 7px 10px;
  font-family: var(--font-mono);
  font-size: .8rem;
  outline: none;
  transition: border-color .15s;
  color: var(--text-primary);
}
.prompt-input:focus { border-color: var(--accent-mid); }
.prompt-input::placeholder { color: var(--text-tertiary); }

/* generation controls */
.controls-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
}
.ctrl-group label {
  display: block;
  font-size: .72rem;
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: 4px;
}
.ctrl-group input[type=range] {
  width: 100%;
  accent-color: var(--accent);
  cursor: pointer;
}
.ctrl-group input[type=number] {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 5px 8px;
  font-size: .8rem;
  outline: none;
  text-align: center;
  color: var(--text-primary);
}
.ctrl-group input[type=number]:focus { border-color: var(--accent-mid); }
.speed-val {
  font-size: .72rem;
  color: var(--accent);
  font-weight: 600;
  font-variant-numeric: tabular-nums;
}
.step-counter {
  font-size: .8rem;
  color: var(--text-secondary);
  text-align: center;
  padding: 4px 0;
}
.step-counter b { color: var(--text-primary); font-variant-numeric: tabular-nums; }

/* ── BUTTONS ────────────────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  border: none;
  border-radius: var(--radius-sm);
  font-family: var(--font);
  font-size: .82rem;
  font-weight: 600;
  cursor: pointer;
  transition: background .15s, opacity .15s, transform .08s;
  padding: 7px 14px;
  white-space: nowrap;
}
.btn:active { transform: scale(.97); }
.btn:disabled { opacity: .45; cursor: default; transform: none; }

.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover:not(:disabled) { background: var(--accent-hover); }

.btn-secondary {
  background: var(--surface-2);
  color: var(--text-primary);
  border: 1px solid var(--border);
}
.btn-secondary:hover:not(:disabled) { background: var(--border); }

.btn-auto {
  background: var(--surface-2);
  color: var(--text-secondary);
  border: 1px solid var(--border);
}
.btn-auto.active {
  background: #fee2e2;
  color: #dc2626;
  border-color: #fca5a5;
}

.btn-next {
  font-size: .9rem;
  padding: 9px 20px;
  min-width: 140px;
}

.action-row {
  display: flex;
  gap: 8px;
  align-items: center;
}

/* ── RIGHT PANEL ────────────────────────────────────── */
.panel-right {
  display: flex;
  flex-direction: column;
  gap: 12px;
  min-height: 0;
}

.gen-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}
.gen-header-left {
  display: flex;
  align-items: center;
  gap: 10px;
}
.gen-label {
  font-size: .7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .07em;
  color: var(--text-tertiary);
}

/* output area */
.output-card {
  flex: 1;
  min-height: 0;
  display: flex;
  flex-direction: column;
}
.output-area {
  flex: 1;
  overflow-y: auto;
  font-family: var(--font-mono);
  font-size: .9rem;
  line-height: 1.9;
  color: var(--text-primary);
  padding: 4px 2px;
  word-wrap: break-word;
}
.output-area:empty::after {
  content: 'Generated text will appear here…';
  color: var(--text-tertiary);
  font-style: italic;
  font-family: var(--font);
  font-size: .85rem;
}
.output-prompt { color: var(--text-secondary); }

/* token animation */
.token {
  display: inline;
  border-radius: 3px;
  padding: 1px 1px;
  transition: background .3s ease;
}
@keyframes tokenFlash {
  0%   { background: var(--token-flash-bg); color: var(--token-flash-fg); transform: scale(1.1); border-radius: 3px; }
  55%  { background: var(--token-flash-bg); color: var(--token-flash-fg); }
  100% { background: transparent; color: inherit; transform: scale(1); }
}
.token--new {
  animation: tokenFlash .55s ease-out forwards;
  display: inline-block;
}
.token--recent { background: var(--token-recent-bg); }

/* top-5 panel */
.top5-card { flex-shrink: 0; }
.top5-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 10px;
}
.context-badge {
  font-size: .72rem;
  color: var(--text-secondary);
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 2px 8px;
  font-family: var(--font-mono);
  max-width: 260px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.top5-rows { display: flex; flex-direction: column; gap: 5px; }
.top5-row {
  display: grid;
  grid-template-columns: 100px 1fr 54px 20px;
  align-items: center;
  gap: 8px;
  padding: 3px 0;
  border-radius: 4px;
  transition: background .15s;
}
.top5-row.chosen { background: var(--accent-light); padding: 3px 6px; }
.top5-word {
  font-family: var(--font-mono);
  font-size: .78rem;
  font-weight: 500;
  color: var(--text-primary);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.top5-row.chosen .top5-word { color: var(--accent); }
.bar-track {
  height: 8px;
  background: var(--surface-2);
  border-radius: 4px;
  overflow: hidden;
}
.bar-fill {
  height: 100%;
  background: var(--accent-mid);
  border-radius: 4px;
  transition: width .35s cubic-bezier(.34, 1.3, .64, 1);
  width: 0%;
}
.top5-row.chosen .bar-fill { background: var(--accent); }
.top5-pct {
  font-size: .75rem;
  color: var(--text-secondary);
  text-align: right;
  font-variant-numeric: tabular-nums;
  font-family: var(--font-mono);
}
.top5-row.chosen .top5-pct { color: var(--accent); font-weight: 600; }
.chosen-mark { font-size: .75rem; color: var(--accent); text-align: center; }
.top5-empty {
  text-align: center;
  color: var(--text-tertiary);
  font-size: .8rem;
  font-style: italic;
  padding: 8px 0;
}

/* ── THEORY PANEL ───────────────────────────────────── */
#theory-panel {
  flex-shrink: 0;
  max-height: 0;
  overflow: hidden;
  transition: max-height .4s cubic-bezier(.4,0,.2,1), opacity .3s ease;
  opacity: 0;
  background: var(--bg);
}
#theory-panel.open {
  max-height: 260px;
  opacity: 1;
  padding-bottom: 16px;
}
.theory-inner {
  display: grid;
  grid-template-columns: 320px 1fr;
  gap: 16px;
  padding: 0 16px;
}
.theory-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 16px;
}
.theory-title {
  font-size: .68rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: var(--text-tertiary);
  margin-bottom: 10px;
}

/* math fraction notation */
.frac {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  vertical-align: middle;
  margin: 0 3px;
  gap: 2px;
}
.frac .num { border-bottom: 1.5px solid var(--text-primary); padding-bottom: 2px; }
.frac .num, .frac .denom { line-height: 1.3; font-size: .82rem; }
.mvar { font-style: italic; color: var(--accent); font-weight: 600; }
.mctx { color: var(--accent); font-weight: 600; font-family: var(--font-mono); }
.math-line {
  font-size: .82rem;
  line-height: 2;
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 4px;
  color: var(--text-primary);
}
.math-line .op { color: var(--text-secondary); margin: 0 2px; }

/* live calculation */
.calc-row {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 4px 12px;
  font-size: .8rem;
  line-height: 1.9;
}
.calc-label { color: var(--text-secondary); white-space: nowrap; }
.calc-val { font-family: var(--font-mono); font-weight: 500; color: var(--text-primary); }
.calc-val .hi { color: var(--accent); font-weight: 700; }
.calc-val .eq { color: var(--text-secondary); margin: 0 4px; }
.calc-note { font-size: .72rem; color: var(--text-tertiary); margin-top: 6px; font-style: italic; }
.theory-placeholder { color: var(--text-tertiary); font-size: .8rem; font-style: italic; padding: 8px 0; }

/* header buttons */
.btn-explain {
  margin-left: auto;
  font-size: .78rem;
  padding: 5px 12px;
  text-decoration: none;
}
.btn-theory {
  margin-left: 8px;
  font-size: .78rem;
  padding: 5px 12px;
}
.btn-theory.active { background: var(--accent-light); color: var(--accent); border-color: var(--accent-mid); }

/* scrollbar */
::-webkit-scrollbar { width: 5px; height: 5px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--text-tertiary); }