:root {
  --bg: #0d1117;
  --bg-raised: #161b22;
  --bg-sunken: #010409;
  --border: #30363d;
  --border-soft: #21262d;
  --fg: #e6edf3;
  --fg-dim: #8b949e;
  --fg-dimmer: #6e7681;
  --blue: #58a6ff;
  --green: #56d364;
  --red: #f85149;
  --yellow: #d29922;
  --purple: #d2a8ff;
  --mono: 'Menlo', 'Monaco', 'Cascadia Code', 'Consolas', 'Courier New', monospace;
}

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

html, body {
  margin: 0;
  min-height: 100%;
  background: var(--bg);
  color: var(--fg);
}

body {
  font-family: var(--mono);
  font-size: 13px;
  line-height: 1.5;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

button {
  font-family: inherit;
}

/* ── top bar ── */
.topbar {
  border-bottom: 1px solid var(--border);
  background: var(--bg-raised);
  padding: 14px 20px;
  flex-shrink: 0;
}

.brand {
  font-size: 17px;
  font-weight: 700;
  letter-spacing: 0.01em;
  color: var(--fg);
}

.brand::before {
  content: '⟨ ⟩ ';
  color: var(--blue);
}

.tag {
  color: var(--fg-dim);
  font-size: 12px;
  margin-top: 3px;
}

/* ── layout ── */
.layout {
  flex: 1;
  display: grid;
  grid-template-columns: 380px 1fr;
  gap: 16px;
  padding: 16px 20px 20px;
  max-width: 1320px;
  width: 100%;
  margin: 0 auto;
  min-height: 0;
}

.col {
  display: flex;
  flex-direction: column;
  min-height: 0;
  min-width: 0;
}

.panel-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 8px;
  margin-bottom: 6px;
}

.panel-head h2 {
  font-size: 11px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--fg-dimmer);
  margin: 0;
  font-weight: 600;
}

.templates-head, .input-head { margin-top: 16px; }

.skipws {
  display: flex;
  align-items: center;
  gap: 5px;
  color: var(--fg-dim);
  font-size: 11px;
  cursor: pointer;
  user-select: none;
}

.skipws input { accent-color: var(--blue); }

/* ── grammar / input text areas ── */
textarea {
  width: 100%;
  background: var(--bg-sunken);
  color: var(--fg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 10px 11px;
  font-family: var(--mono);
  font-size: 13px;
  line-height: 1.6;
  resize: vertical;
  outline: none;
}

textarea:focus {
  border-color: var(--blue);
}

#grammarInput { min-height: 150px; }
#inputString { min-height: 44px; }

.err-banner {
  margin-top: 6px;
  background: rgba(248, 81, 73, 0.1);
  border: 1px solid rgba(248, 81, 73, 0.4);
  color: var(--red);
  border-radius: 6px;
  padding: 7px 10px;
  font-size: 12px;
  line-height: 1.5;
}

/* ── templates ── */
.templates {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.template-group-label {
  font-size: 10px;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--fg-dimmer);
  margin: 8px 0 1px;
}

.template-group-label:first-child {
  margin-top: 0;
}

.template-btn {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 1px;
  background: var(--bg-raised);
  border: 1px solid var(--border-soft);
  border-radius: 6px;
  padding: 7px 10px;
  color: var(--fg);
  cursor: pointer;
  text-align: left;
}

.template-btn:hover, .template-btn:focus-visible {
  border-color: var(--blue);
  outline: none;
}

.t-name {
  color: var(--blue);
  font-size: 12.5px;
  font-weight: 600;
}

.t-blurb {
  color: var(--fg-dimmer);
  font-size: 11px;
  line-height: 1.4;
}

/* ── actions ── */
.actions {
  margin-top: 14px;
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.btn {
  background: var(--bg-raised);
  border: 1px solid var(--border);
  color: var(--fg);
  border-radius: 6px;
  padding: 7px 12px;
  font-size: 12.5px;
  cursor: pointer;
  white-space: nowrap;
}

.btn:hover:not(:disabled), .btn:focus-visible:not(:disabled) {
  border-color: var(--blue);
  outline: none;
}

.btn:disabled { opacity: 0.4; cursor: default; }

.btn-primary {
  background: #1f6feb;
  border-color: #1f6feb;
  color: #fff;
  font-weight: 600;
}
.btn-primary:hover { background: #388bfd; border-color: #388bfd; }

.btn-accent {
  border-color: var(--green);
  color: var(--green);
}

kbd {
  font-family: inherit;
  font-size: 10px;
  background: rgba(255,255,255,0.12);
  padding: 1px 4px;
  border-radius: 3px;
}

.rule-note {
  color: var(--fg-dimmer);
  font-size: 11.5px;
}

/* ── run column ── */
.verdict {
  border-radius: 6px;
  padding: 9px 12px;
  font-size: 12.5px;
  margin-bottom: 10px;
  border: 1px solid var(--border);
  flex-shrink: 0;
}
.v-ok { background: rgba(86, 211, 100, 0.1); border-color: rgba(86, 211, 100, 0.4); color: var(--green); }
.v-fail { background: rgba(248, 81, 73, 0.1); border-color: rgba(248, 81, 73, 0.4); color: var(--red); }
.v-warn { background: rgba(210, 153, 34, 0.1); border-color: rgba(210, 153, 34, 0.4); color: var(--yellow); }

.ruler-wrap {
  flex-shrink: 0;
  margin-bottom: 10px;
}

.ruler-label {
  font-size: 10px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--fg-dimmer);
  margin-bottom: 4px;
}

.ruler {
  background: var(--bg-sunken);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 10px 11px;
  font-size: 14px;
  line-height: 1.7;
  min-height: 20px;
  overflow-x: auto;
  white-space: nowrap;
}

.ruler .ch { position: relative; }
.ruler .ch.consumed {
  background: rgba(86, 211, 100, 0.28);
  border-radius: 2px;
  color: var(--fg);
}
.ruler .ws { color: var(--fg-dimmer); }
.ruler .ch.empty { color: var(--fg-dimmer); font-style: italic; }

.caret {
  display: inline-block;
  width: 0;
  border-left: 2px solid var(--blue);
  height: 1.1em;
  vertical-align: -0.2em;
  margin: 0 -1px;
  animation: blink 0.9s steps(1) infinite;
}
.caret-try { border-color: var(--blue); }
.caret-fail { border-color: var(--red); animation: none; box-shadow: 0 0 0 3px rgba(248,81,73,0.25); }
.caret-zero { border-color: var(--green); }

@keyframes blink { 50% { opacity: 0.25; } }

/* ── controls ── */
.controls {
  display: flex;
  align-items: center;
  gap: 6px;
  flex-wrap: wrap;
  margin-bottom: 10px;
  flex-shrink: 0;
}

.speed {
  display: flex;
  align-items: center;
  gap: 5px;
  color: var(--fg-dimmer);
  font-size: 11px;
  margin-left: 4px;
}

.speed input { accent-color: var(--blue); }

.step-counter {
  margin-left: auto;
  color: var(--fg-dimmer);
  font-size: 11.5px;
  white-space: nowrap;
}

/* ── tabs ── */
.tabs {
  display: flex;
  gap: 2px;
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}

.tab {
  background: transparent;
  border: none;
  border-bottom: 2px solid transparent;
  color: var(--fg-dimmer);
  padding: 7px 12px;
  font-size: 12px;
  cursor: pointer;
  font-family: inherit;
}

.tab:hover { color: var(--fg); }

.tab.active {
  color: var(--fg);
  border-bottom-color: var(--blue);
}

.tab-panel {
  flex: 1;
  min-height: 0;
  overflow-y: auto;
  background: var(--bg-sunken);
  border: 1px solid var(--border);
  border-top: none;
  border-radius: 0 0 6px 6px;
  padding: 10px 12px;
}

.empty-hint {
  color: var(--fg-dimmer);
  font-size: 12.5px;
  padding: 10px 0;
}

/* ── trace tree ── */
.node-children {
  margin-left: 8px;
  padding-left: 10px;
  border-left: 1px solid var(--border-soft);
}

.node-head {
  display: flex;
  align-items: baseline;
  gap: 6px;
  flex-wrap: wrap;
  padding: 2px 5px;
  border-radius: 4px;
  font-size: 12px;
  line-height: 1.55;
}

.node-head.current {
  background: rgba(88, 166, 255, 0.14);
  outline: 1px solid rgba(88, 166, 255, 0.5);
}

.status-pending .k-rule, .status-pending .k-term, .status-pending .k-struct { color: var(--yellow); }
.status-ok .k-rule { color: var(--blue); }
.status-ok .k-term { color: var(--purple); }
.status-ok .k-struct { color: var(--fg-dim); }
.status-fail .k-rule, .status-fail .k-term, .status-fail .k-struct { color: var(--red); text-decoration: line-through; text-decoration-color: rgba(248,81,73,0.5); }

.at { color: var(--fg-dimmer); font-size: 10.5px; }
.matched { color: var(--green); font-size: 11px; }
.note { color: var(--fg-dimmer); font-size: 10.5px; font-style: italic; }
.pending-note { color: var(--yellow); }

.tag {
  font-size: 9px;
  padding: 0 4px;
  border-radius: 3px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}
.tag-cache { background: rgba(210, 168, 255, 0.18); color: var(--purple); }

/* ── clean parse tree ── */
.clean-node {
  margin: 1px 0;
}
.clean-node > summary {
  cursor: pointer;
  color: var(--blue);
  font-size: 12.5px;
  padding: 2px 4px;
  border-radius: 4px;
  list-style: none;
}
.clean-node > summary::-webkit-details-marker { display: none; }
.clean-node > summary::before {
  content: '▸ ';
  color: var(--fg-dimmer);
}
.clean-node[open] > summary::before { content: '▾ '; }
.clean-node > *:not(summary) {
  margin-left: 16px;
  padding-left: 8px;
  border-left: 1px solid var(--border-soft);
}
.clean-leaf {
  padding: 2px 4px 2px 20px;
  font-size: 12.5px;
}

/* ── help tab ── */
.help p { margin: 0 0 10px; color: var(--fg-dim); font-size: 12.5px; line-height: 1.6; }
.help table { border-collapse: collapse; width: 100%; margin-bottom: 12px; }
.help td { padding: 4px 8px; border-bottom: 1px solid var(--border-soft); font-size: 12px; vertical-align: top; }
.help td:first-child { white-space: nowrap; color: var(--purple); width: 1%; }
.help code { background: rgba(255,255,255,0.06); padding: 1px 4px; border-radius: 3px; }
.help-note { color: var(--fg-dimmer); font-size: 11.5px; }

/* ── footer ── */
.footer {
  text-align: center;
  padding: 12px 0 16px;
  font-size: 12px;
  color: var(--fg-dimmer);
  flex-shrink: 0;
}
.footer a { color: var(--fg-dimmer); text-decoration: none; }
.footer a:hover { color: var(--fg); }

/* ── scrollbars ── */
.tab-panel::-webkit-scrollbar, .ruler::-webkit-scrollbar { width: 8px; height: 8px; }
.tab-panel::-webkit-scrollbar-thumb, .ruler::-webkit-scrollbar-thumb { background: var(--border); border-radius: 4px; }

/* ── mobile ── */
@media (max-width: 860px) {
  .layout {
    grid-template-columns: 1fr;
    padding: 12px 10px 16px;
  }
  .col-run { min-height: 60vh; }
  .controls { justify-content: flex-start; }
  .step-counter { margin-left: 0; width: 100%; order: 10; }
}