@import url('https://fonts.googleapis.com/css2?family=Bitter:wght@500;700&family=Source+Sans+3:wght@400;600;700&family=IBM+Plex+Mono:wght@400;500;600&display=swap');

:root {
  --paper: #efe7d8;
  --canvas: #f7f1e6;
  --panel: rgba(255, 250, 241, 0.94);
  --panel-strong: rgba(255, 247, 234, 0.98);
  --ink: #24303a;
  --muted: #5f6972;
  --line: rgba(36, 48, 58, 0.14);
  --line-strong: rgba(36, 48, 58, 0.24);
  --blue: #2563eb;
  --blue-soft: rgba(37, 99, 235, 0.10);
  --teal: #0f766e;
  --teal-soft: rgba(15, 118, 110, 0.10);
  --green: #15803d;
  --green-soft: rgba(21, 128, 61, 0.10);
  --amber: #a04a08;
  --amber-soft: rgba(160, 74, 8, 0.10);
  --red: #b91c1c;
  --red-soft: rgba(185, 28, 28, 0.10);
  --page-sheen: linear-gradient(180deg, rgba(255,255,255,0.55), rgba(255,255,255,0.12));
  --radius-lg: 24px;
  --radius-md: 16px;
  --radius-sm: 12px;
  --shadow: 0 18px 36px rgba(42, 34, 28, 0.08);
  --font-body: "Source Sans 3", Georgia, serif;
  --font-display: "Bitter", Georgia, serif;
  --font-mono: "IBM Plex Mono", monospace;
}

@media (prefers-color-scheme: dark) {
  :root {
    --paper: #1c1916;
    --canvas: #141210;
    --panel: rgba(32, 28, 24, 0.94);
    --panel-strong: rgba(36, 32, 28, 0.98);
    --ink: #f4efe6;
    --muted: #c8d1d7;
    --line: rgba(200, 209, 215, 0.14);
    --line-strong: rgba(200, 209, 215, 0.26);
    --blue: #60a5fa;
    --blue-soft: rgba(96, 165, 250, 0.12);
    --teal: #2dd4bf;
    --teal-soft: rgba(45, 212, 191, 0.12);
    --green: #4ade80;
    --green-soft: rgba(74, 222, 128, 0.12);
    --amber: #f5b731;
    --amber-soft: rgba(245, 183, 49, 0.12);
    --red: #f87171;
    --red-soft: rgba(248, 113, 113, 0.12);
    --page-sheen: linear-gradient(180deg, rgba(255,255,255,0.03), rgba(255,255,255,0.00));
    --shadow: 0 18px 36px rgba(0, 0, 0, 0.25);
  }
}

* { box-sizing: border-box; }
body {
  margin: 0;
  padding: 20px;
  font-family: var(--font-body);
  color: var(--ink);
  background:
    radial-gradient(circle at top left, rgba(15, 118, 110, 0.08), transparent 34%),
    radial-gradient(circle at top right, rgba(37, 99, 235, 0.08), transparent 34%),
    var(--page-sheen),
    var(--canvas);
}
.shell { max-width: 1180px; margin: 0 auto; }
.hero { text-align: center; padding: 24px 0 18px; }
.hero h1 { margin: 0; font-family: var(--font-display); font-size: 2rem; }
.hero p { margin: 10px auto 0; max-width: 820px; color: var(--muted); }
.lab-nav {
  display: flex;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
  margin: 0 0 16px;
}
.lab-nav a {
  padding: 8px 12px;
  border-radius: 999px;
  border: 1px solid var(--line-strong);
  background: var(--panel-strong);
  color: var(--ink);
  text-decoration: none;
  box-shadow: var(--shadow);
  font-size: 0.82rem;
}
.formula {
  margin: 0 auto 16px;
  max-width: 860px;
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--line);
  background: var(--panel-strong);
  box-shadow: var(--shadow);
  text-align: center;
  font-family: var(--font-mono);
  font-size: 0.8rem;
}
.intro-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
  margin: 0 0 16px;
}
@media (max-width: 800px) {
  .intro-grid { grid-template-columns: 1fr; }
}
.intro-card {
  padding: 16px 18px;
  border-radius: var(--radius-md);
  border: 1px solid var(--line);
  background: var(--panel-strong);
  box-shadow: var(--shadow);
}
.intro-card h2 { margin: 0 0 8px; font-family: var(--font-display); font-size: 1rem; }
.intro-card p { margin: 0; color: var(--muted); }
.controls,
.panel {
  background: var(--panel-strong);
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
}
.controls {
  border-radius: var(--radius-md);
  padding: 16px 18px;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 14px;
  margin-bottom: 12px;
}
@media (max-width: 900px) {
  .controls { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 560px) {
  .controls { grid-template-columns: 1fr; }
}
.control label {
  display: block;
  margin-bottom: 6px;
  font-size: 0.82rem;
  font-weight: 700;
}
.control input,
.control select,
.control button {
  width: 100%;
  font-family: var(--font-mono);
  font-size: 0.82rem;
}
.control input,
.control select {
  padding: 8px 10px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--line-strong);
  background: var(--panel);
  color: var(--ink);
}
.control button {
  padding: 10px 12px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--line-strong);
  background: var(--panel);
  color: var(--ink);
  cursor: pointer;
}
.btn-blue { background: var(--blue-soft); color: var(--blue); border-color: rgba(37, 99, 235, 0.25); }
.btn-green { background: var(--green-soft); color: var(--green); border-color: rgba(21, 128, 61, 0.25); }
.btn-teal { background: var(--teal-soft); color: var(--teal); border-color: rgba(15, 118, 110, 0.25); }
.btn-red { background: var(--red-soft); color: var(--red); border-color: rgba(185, 28, 28, 0.25); }
.summary-banner {
  margin: 0 0 16px;
  padding: 14px 16px;
  border-radius: var(--radius-md);
  border: 1px solid rgba(15, 118, 110, 0.22);
  background: var(--teal-soft);
  box-shadow: var(--shadow);
}
.summary-banner strong {
  display: block;
  margin-bottom: 4px;
  font-family: var(--font-display);
}
.grid { display: grid; grid-template-columns: 1.1fr 1fr; gap: 16px; }
@media (max-width: 920px) {
  .grid { grid-template-columns: 1fr; }
}
.panel { border-radius: var(--radius-lg); padding: 18px; }
.panel h2 { margin: 0 0 12px; font-family: var(--font-display); font-size: 1.08rem; }
.panel h3 { margin: 18px 0 8px; color: var(--muted); font-size: 0.9rem; }
.row { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
@media (max-width: 720px) {
  .row { grid-template-columns: 1fr; }
}
.compare-card {
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 12px;
  background: rgba(255,255,255,0.42);
}
.compare-card h4 { margin: 0 0 8px; font-family: var(--font-display); font-size: 0.96rem; }
.compare-card p { margin: 4px 0; font-family: var(--font-mono); font-size: 0.76rem; }
pre {
  margin: 0;
  padding: 14px;
  border-radius: var(--radius-md);
  border: 1px solid var(--line);
  background: rgba(0,0,0,0.03);
  font-family: var(--font-mono);
  font-size: 0.77rem;
  overflow-x: auto;
  white-space: pre-wrap;
}
.log {
  max-height: 300px;
  overflow-y: auto;
  padding: 12px;
  border-radius: var(--radius-md);
  border: 1px solid var(--line);
  background: rgba(0,0,0,0.03);
  font-family: var(--font-mono);
  font-size: 0.76rem;
  line-height: 1.55;
  white-space: pre-wrap;
}
.chips,
.sample-list,
.chip-row { display: flex; flex-wrap: wrap; gap: 8px; }
.chip {
  padding: 6px 10px;
  border-radius: 999px;
  font-family: var(--font-mono);
  font-size: 0.74rem;
  border: 1px solid var(--line-strong);
  background: rgba(255,255,255,0.42);
}
.chip.good { background: var(--green-soft); color: var(--green); border-color: rgba(21, 128, 61, 0.22); }
.chip.warn { background: var(--amber-soft); color: var(--amber); border-color: rgba(160, 74, 8, 0.22); }
.chip.bad { background: var(--red-soft); color: var(--red); border-color: rgba(185, 28, 28, 0.22); }
.note {
  margin-top: 14px;
  padding: 12px 14px;
  border-radius: var(--radius-md);
  border-left: 4px solid var(--teal);
  background: var(--teal-soft);
  font-size: 0.88rem;
}