:root {
  --bg: #0f1419;
  --panel: #1a222c;
  --text: #e7ecf1;
  --muted: #9aa7b5;
  --accent: #7aa2ff;
  --ok: #3dd68c;
  --no: #ff6b7a;
  --border: #2a3542;
  --font: "IBM Plex Sans", system-ui, sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, monospace;
}

* { box-sizing: border-box; }
html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  line-height: 1.5;
}
a { color: var(--accent); }
main {
  max-width: 980px;
  margin: 0 auto;
  padding: 1.5rem 1.25rem 3rem;
}
header h1 {
  margin: 0 0 0.35rem;
  font-size: 1.65rem;
  letter-spacing: -0.02em;
}
.site-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem 1rem;
  margin: 0 0 1rem;
  font-size: 0.92rem;
}
.site-nav a[aria-current="page"] {
  font-weight: 600;
  border-bottom: 2px solid var(--accent);
  padding-bottom: 0.1rem;
}
header .sub {
  color: var(--muted);
  margin: 0 0 1.25rem;
  max-width: 46rem;
}
.panel {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1rem 1.1rem;
  margin-bottom: 1rem;
}
.panel h2 {
  margin: 0 0 0.75rem;
  font-size: 1.05rem;
}
.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  align-items: center;
  margin-bottom: 0.75rem;
}
label { font-size: 0.9rem; color: var(--muted); }
input[type="text"] {
  flex: 1 1 220px;
  min-width: 180px;
  background: #0c1015;
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 8px;
  padding: 0.5rem 0.7rem;
  font-family: var(--mono);
  font-size: 0.95rem;
}
button {
  background: #243044;
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.45rem 0.85rem;
  cursor: pointer;
  font: inherit;
  font-size: 0.9rem;
}
button:hover { border-color: var(--accent); }
button.primary {
  background: #2a4a8a;
  border-color: #3d6bc4;
}
button.okish {
  background: #1e4a38;
  border-color: #2d7a58;
}
.move-pad {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  margin-top: 0.5rem;
}
.move-pad button {
  font-family: var(--mono);
  min-width: 2.4rem;
  padding: 0.35rem 0.5rem;
}
#status { margin: 0.5rem 0; }
.pill {
  display: inline-block;
  font-family: var(--mono);
  font-size: 0.85rem;
  background: #0c1015;
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 0.15rem 0.65rem;
  margin-right: 0.35rem;
}
.pill.ok { border-color: var(--ok); color: var(--ok); }
.pill.no { border-color: var(--no); color: var(--no); }
.muted { color: var(--muted); font-size: 0.9rem; }
#tokens {
  font-family: var(--mono);
  font-size: 0.82rem;
  color: var(--muted);
  word-break: break-word;
}
#error {
  color: var(--no);
  font-family: var(--mono);
  font-size: 0.85rem;
  margin: 0.4rem 0 0;
}
#net {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  align-items: flex-start;
  overflow-x: auto;
  padding: 0.25rem 0;
}
.net-row {
  display: flex;
  gap: 0.35rem;
}
.face {
  position: relative;
  width: 96px;
  flex: 0 0 96px;
}
.face-empty { width: 96px; height: 96px; visibility: hidden; }
.face-label {
  position: absolute;
  top: -0.9rem;
  left: 0;
  font-size: 0.7rem;
  color: var(--muted);
  font-family: var(--mono);
}
.grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 3px;
  width: 96px;
  height: 96px;
  background: #080b0f;
  padding: 3px;
  border-radius: 6px;
  border: 1px solid var(--border);
}
.cell {
  border-radius: 3px;
  border: 1px solid rgba(0,0,0,0.35);
}
.layout-2col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}
@media (max-width: 760px) {
  .layout-2col { grid-template-columns: 1fr; }
}
#rings-svg { display: flex; justify-content: center; }
#rings-text {
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--muted);
  white-space: pre-wrap;
  margin: 0.5rem 0 0;
}
.math {
  font-size: 0.95rem;
}
.math ul { padding-left: 1.2rem; }
.math code, footer code, #run-demo code {
  font-family: var(--mono);
  font-size: 0.88em;
  background: #0c1015;
  padding: 0.05em 0.35em;
  border-radius: 4px;
}
.run-pre {
  font-family: var(--mono);
  font-size: 0.8rem;
  background: #0c1015;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.75rem 0.9rem;
  overflow-x: auto;
  white-space: pre-wrap;
  color: var(--muted);
  margin: 0.5rem 0 0.75rem;
}
footer {
  margin-top: 1.5rem;
  color: var(--muted);
  font-size: 0.85rem;
  border-top: 1px solid var(--border);
  padding-top: 1rem;
}