:root {
  --bg: #fafafa;
  --fg: #1a1a1a;
  --muted: #666;
  --accent: #4a3aff;
  --accent-soft: #e9e7ff;
  --eml-color: #4a3aff;
  --one-color: #2c8a3e;
  --var-color: #c44a3a;
  --border: #d6d6d6;
  --code-bg: #f3f3f3;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue",
               sans-serif;
  background: var(--bg);
  color: var(--fg);
  line-height: 1.5;
}

header {
  background: white;
  border-bottom: 1px solid var(--border);
  padding: 24px 32px;
}

header h1 {
  margin: 0 0 6px 0;
  font-size: 26px;
  font-weight: 700;
}

header .sub {
  margin: 0;
  color: var(--muted);
  font-size: 14px;
  max-width: 800px;
}

main {
  max-width: 1100px;
  margin: 24px auto;
  padding: 0 32px;
}

.input-row {
  display: flex;
  gap: 12px;
  align-items: center;
  margin-bottom: 12px;
}

.input-row label {
  font-family: "SF Mono", Menlo, monospace;
  font-size: 16px;
  font-weight: 600;
}

.input-row input {
  flex: 1;
  padding: 10px 14px;
  font-family: "SF Mono", Menlo, monospace;
  font-size: 16px;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: white;
}

.input-row input:focus {
  outline: 2px solid var(--accent);
  outline-offset: -1px;
}

.input-row button {
  padding: 10px 20px;
  background: var(--accent);
  color: white;
  border: none;
  border-radius: 6px;
  font-size: 15px;
  font-weight: 500;
  cursor: pointer;
}

.input-row button:hover { filter: brightness(1.05); }

.examples {
  margin-bottom: 24px;
  font-size: 13px;
  color: var(--muted);
}

.example-group {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  align-items: center;
  margin-bottom: 8px;
}

.example-label {
  display: inline-block;
  min-width: 230px;
  font-weight: 600;
  color: var(--fg);
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.examples button.ex {
  padding: 4px 10px;
  background: white;
  border: 1px solid var(--border);
  border-radius: 4px;
  cursor: pointer;
  font-family: "SF Mono", Menlo, monospace;
  font-size: 13px;
}

.examples button.ex:hover {
  background: var(--accent-soft);
  border-color: var(--accent);
}

.error {
  background: #ffe9e9;
  border: 1px solid #ffb3b3;
  color: #8a1a1a;
  padding: 12px 16px;
  border-radius: 6px;
  margin-bottom: 16px;
  font-family: "SF Mono", Menlo, monospace;
  font-size: 13px;
}

.projection {
  background: #eef7ff;
  border: 1px solid #a3cfff;
  color: #1a3a6e;
  padding: 10px 14px;
  border-radius: 6px;
  margin-bottom: 16px;
  font-size: 14px;
}

.domain {
  background: #f4f0ff;
  border: 1px solid #c8b8ee;
  color: #3a1a6e;
  padding: 10px 14px;
  border-radius: 6px;
  margin-bottom: 12px;
  font-size: 14px;
}

.grammar-tag {
  display: inline-block;
  font-size: 11px;
  padding: 2px 8px;
  border-radius: 999px;
  margin-left: 6px;
  font-family: "SF Mono", Menlo, monospace;
}
.grammar-tag.real    { background: #d8efe0; color: #15532b; }
.grammar-tag.complex { background: #ead8ef; color: #4a1559; }

.references {
  background: #fbfbfd;
  border: 1px solid #e2e2ec;
  border-left: 3px solid var(--accent);
  border-radius: 6px;
  padding: 12px 16px;
  margin-bottom: 18px;
  font-size: 13.5px;
  line-height: 1.55;
}
.references > strong { color: var(--accent); }
.references ul {
  margin: 6px 0 0 0;
  padding-left: 0;
  list-style: none;
}
.references li {
  padding: 3px 0;
}
.references a { color: var(--accent); text-decoration: underline; }

.ref-tag {
  display: inline-block;
  width: 44px;
  font-size: 11px;
  text-align: center;
  padding: 1px 6px;
  margin-right: 6px;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent);
  font-family: "SF Mono", Menlo, monospace;
  font-weight: 600;
}

.cite {
  font-size: 10.5px;
  color: #777;
  font-weight: normal;
  margin-left: 4px;
}
button.ex .cite { font-family: "SF Mono", Menlo, monospace; }

.metrics {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 12px;
  margin-bottom: 20px;
}

.metric {
  background: white;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 16px;
  text-align: center;
}

.metric .label {
  display: block;
  font-size: 12px;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.metric .value {
  display: block;
  font-size: 32px;
  font-weight: 700;
  color: var(--accent);
  font-family: "SF Mono", Menlo, monospace;
  margin-top: 4px;
}

.rpn {
  margin-bottom: 20px;
}

.rpn h3, .tree h3, .info h3 {
  margin: 0 0 8px 0;
  font-size: 14px;
  font-weight: 600;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

#rpn-output {
  background: white;
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 12px 16px;
  font-family: "SF Mono", Menlo, monospace;
  font-size: 13px;
  overflow-x: auto;
  white-space: pre-wrap;
  word-break: break-all;
  margin: 0;
}

.tree {
  margin-bottom: 32px;
}

.tree .hint {
  font-size: 13px;
  color: var(--muted);
  margin: 0 0 12px 0;
}

.legend-box {
  display: inline-block;
  width: 12px;
  height: 12px;
  border-radius: 2px;
  vertical-align: middle;
  margin: 0 2px;
}

.legend-box.eml { background: var(--eml-color); }
.legend-box.one { background: var(--one-color); }
.legend-box.var { background: var(--var-color); }
.legend-box.realize { background: #b8860b; }

#tree-container {
  background: white;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 16px;
  overflow: auto;
  min-height: 200px;
}

#tree-svg {
  display: block;
  margin: 0 auto;
}

.node-eml {
  fill: var(--eml-color);
  cursor: pointer;
}

.node-one {
  fill: var(--one-color);
}

.node-var {
  fill: var(--var-color);
}

.node-realize {
  fill: #b8860b;
  cursor: help;
}

.node-label {
  fill: white;
  font-family: "SF Mono", Menlo, monospace;
  font-size: 11px;
  font-weight: 700;
  text-anchor: middle;
  pointer-events: none;
}

.edge {
  stroke: #999;
  stroke-width: 1.5;
  fill: none;
}

.tooltip {
  position: absolute;
  background: rgba(20, 20, 20, 0.95);
  color: white;
  padding: 6px 10px;
  border-radius: 4px;
  font-family: "SF Mono", Menlo, monospace;
  font-size: 12px;
  pointer-events: none;
  max-width: 400px;
  word-wrap: break-word;
  z-index: 100;
}

.info {
  background: white;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 20px 24px;
  margin-bottom: 32px;
}

.info p { margin: 0 0 12px 0; }
.info p.caveat {
  background: #fffbe9;
  border: 1px solid #ffe6a0;
  padding: 12px 14px;
  border-radius: 6px;
  font-size: 14px;
}

.recipe {
  background: var(--code-bg);
  padding: 12px 14px;
  border-radius: 6px;
  font-family: "SF Mono", Menlo, monospace;
  font-size: 13px;
  margin: 12px 0;
  overflow-x: auto;
}

code {
  font-family: "SF Mono", Menlo, monospace;
  background: var(--code-bg);
  padding: 1px 5px;
  border-radius: 3px;
  font-size: 0.93em;
}

footer {
  border-top: 1px solid var(--border);
  padding: 16px 32px;
  font-size: 13px;
  color: var(--muted);
  text-align: center;
}