/* OCamlCalc — warm amber on deep charcoal. Mobile-first, zero frameworks. */
:root {
  --bg: #1a1206;
  --bg-soft: #241a0d;
  --card: #2a2012;
  --edge: #45351c;
  --ink: #f5edd8;
  --ink-dim: #c9b98f;
  --amber: #ffb347;
  --amber-deep: #e8961e;
  --good: #9ad06a;
  --bad: #ff8a80;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  font-family: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  background:
    radial-gradient(1100px 500px at 85% -10%, rgba(255, 179, 71, 0.09), transparent 60%),
    var(--bg);
  color: var(--ink);
  line-height: 1.55;
}

.skip-link {
  position: absolute;
  left: -999px;
  top: 0;
  background: var(--amber);
  color: #241703;
  padding: 0.5rem 1rem;
  border-radius: 0 0 8px 0;
}
.skip-link:focus { left: 0; }

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.8rem 1rem;
  max-width: 860px;
  margin: 0 auto;
}
.brand { display: flex; align-items: center; gap: 0.6rem; }
.brand img { border-radius: 8px; }
.brand strong { display: block; font-size: 1.05rem; }
.tagline { color: var(--ink-dim); font-size: 0.8rem; display: block; }

select {
  background: var(--bg-soft);
  color: var(--ink);
  border: 1px solid var(--edge);
  border-radius: 8px;
  padding: 0.35rem 0.5rem;
}

main { max-width: 860px; margin: 0 auto; padding: 0 1rem 2rem; }

.hero { text-align: center; padding: 1.4rem 0 1rem; }
.badge-c {
  display: inline-block;
  font-size: 0.72rem;
  letter-spacing: 0.04em;
  color: var(--amber);
  border: 1px solid rgba(255, 179, 71, 0.35);
  border-radius: 999px;
  padding: 0.15rem 0.7rem;
  margin-bottom: 0.6rem;
}
.hero h1 { font-size: 1.6rem; margin: 0.2rem 0 0.5rem; }
.hero p { color: var(--ink-dim); margin: 0 auto; max-width: 46rem; font-size: 0.92rem; }

.tabs {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.4rem;
  margin: 1rem 0 0.8rem;
}
.tab {
  background: var(--bg-soft);
  color: var(--ink-dim);
  border: 1px solid var(--edge);
  border-radius: 10px;
  padding: 0.55rem 0.4rem;
  font-weight: 600;
  cursor: pointer;
}
.tab.active {
  background: linear-gradient(180deg, var(--amber), var(--amber-deep));
  color: #241703;
  border-color: transparent;
}

.card {
  background: var(--card);
  border: 1px solid var(--edge);
  border-radius: 14px;
  padding: 1rem;
  margin-bottom: 1rem;
}

.field { display: flex; flex-direction: column; gap: 0.25rem; margin-bottom: 0.7rem; flex: 1; }
.field label { font-size: 0.8rem; color: var(--ink-dim); }
input {
  background: var(--bg-soft);
  border: 1px solid var(--edge);
  color: var(--ink);
  border-radius: 10px;
  padding: 0.6rem 0.7rem;
  font-size: 1rem;
  width: 100%;
}
input:focus, select:focus {
  outline: 2px solid var(--amber);
  outline-offset: 1px;
}

.row2 { display: grid; grid-template-columns: 1fr 1fr; gap: 0.7rem; }
.row3 { display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 0.7rem; }
@media (max-width: 480px) {
  .row3 { grid-template-columns: 1fr; }
}

.actions { display: flex; gap: 0.6rem; margin: 0.4rem 0 0.6rem; flex-wrap: wrap; }
.btn-primary {
  background: linear-gradient(180deg, var(--amber), var(--amber-deep));
  color: #241703;
  font-weight: 700;
  border: none;
  border-radius: 10px;
  padding: 0.6rem 1.2rem;
  cursor: pointer;
}
.btn-primary:hover { filter: brightness(1.07); }
.btn-ghost {
  background: transparent;
  color: var(--amber);
  border: 1px solid rgba(255, 179, 71, 0.4);
  border-radius: 10px;
  padding: 0.6rem 1rem;
  cursor: pointer;
}

.err { color: var(--bad); font-size: 0.88rem; margin: 0.3rem 0; }

.stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 0.6rem;
  margin-top: 0.8rem;
}
.stat {
  background: var(--bg-soft);
  border: 1px solid var(--edge);
  border-radius: 10px;
  padding: 0.55rem 0.7rem;
}
.stat span { display: block; font-size: 0.72rem; color: var(--ink-dim); }
.stat strong { font-size: 1.02rem; overflow-wrap: anywhere; }

details { margin-top: 0.8rem; }
summary { cursor: pointer; color: var(--amber); font-weight: 600; }
.tbl-wrap { max-height: 320px; overflow: auto; margin-top: 0.5rem; border: 1px solid var(--edge); border-radius: 10px; }
.tbl { width: 100%; border-collapse: collapse; font-variant-numeric: tabular-nums; }
.tbl th, .tbl td { padding: 0.42rem 0.6rem; text-align: right; border-bottom: 1px solid var(--edge); }
.tbl th:first-child, .tbl td:first-child { text-align: left; }
.tbl thead th { position: sticky; top: 0; background: var(--bg-soft); color: var(--ink-dim); }
.tbl tbody tr:last-child td { border-bottom: none; }

.why h2 { margin: 0.2rem 0 0.5rem; font-size: 1.15rem; }
.why p { color: var(--ink-dim); font-size: 0.9rem; margin: 0.4rem 0; }

.foot {
  text-align: center;
  color: var(--ink-dim);
  font-size: 0.82rem;
  padding: 1rem 0 2rem;
}
.foot a { color: var(--amber); text-decoration: none; }