/* GradeLab — grade-sheet inspired, mobile-first, no external requests */
:root {
  --paper: #faf8f3;
  --ink: #1f2937;
  --muted: #6b7280;
  --accent: #1d4ed8;
  --accent-soft: #dbeafe;
  --good: #166534;
  --good-bg: #dcfce7;
  --warn: #92400e;
  --warn-bg: #fef3c7;
  --bad: #991b1b;
  --bad-bg: #fee2e2;
  --line: #e5e7eb;
  --radius: 12px;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.6;
}
.site-header {
  padding: 1.5rem 1rem 0.5rem;
  max-width: 640px;
  margin: 0 auto;
}
.brand { font-weight: 800; font-size: 1.4rem; letter-spacing: 0.02em; }
.brand-mark {
  display: inline-block;
  background: var(--ink);
  color: var(--paper);
  border-radius: 8px;
  padding: 0.1rem 0.45rem;
  margin-right: 0.4rem;
  font-size: 1.1rem;
}
.tagline { color: var(--muted); margin: 0.25rem 0 0; font-size: 0.95rem; }
main { max-width: 640px; margin: 0 auto; padding: 0 1rem 3rem; }
h1 { font-size: 1.6rem; line-height: 1.3; margin: 1.25rem 0 0.5rem; }
.intro { color: var(--muted); margin-top: 0; }
h2 { font-size: 1.25rem; margin: 2.5rem 0 0.75rem; }

.tabs {
  display: flex;
  gap: 0.5rem;
  margin: 1.5rem 0 0;
}
.tab {
  flex: 1;
  padding: 0.7rem 0.25rem;
  border: 2px solid var(--line);
  background: #fff;
  border-radius: var(--radius) var(--radius) 0 0;
  border-bottom: none;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  color: var(--muted);
}
.tab.active { color: var(--accent); border-color: var(--accent); background: #fff; }
.panel {
  display: none;
  background: #fff;
  border: 2px solid var(--line);
  border-top: 2px solid var(--line);
  border-radius: 0 var(--radius) var(--radius) var(--radius);
  padding: 1.25rem;
}
.panel.active { display: block; }
.field { margin-bottom: 1rem; }
.field label { display: block; font-weight: 600; margin-bottom: 0.3rem; font-size: 0.95rem; }
.field input[type="number"],
.field input[type="text"],
.field select {
  width: 100%;
  padding: 0.65rem 0.75rem;
  font-size: 1rem;
  border: 2px solid var(--line);
  border-radius: 8px;
  background: var(--paper);
}
.field input:focus, .field select:focus { outline: 2px solid var(--accent); border-color: var(--accent); }
.checkbox-field label { font-weight: 400; display: flex; gap: 0.5rem; align-items: flex-start; }
.checkbox-field input { margin-top: 0.3rem; }
.hint { color: var(--muted); font-size: 0.9rem; margin-top: 0; }
.note { color: var(--muted); font-size: 0.85rem; margin-top: 1rem; }

.calc-btn {
  width: 100%;
  padding: 0.8rem;
  font-size: 1.05rem;
  font-weight: 700;
  color: #fff;
  background: var(--accent);
  border: none;
  border-radius: 8px;
  cursor: pointer;
  margin-top: 0.25rem;
}
.calc-btn:hover { background: #1e40af; }
.ghost-btn {
  padding: 0.5rem 0.9rem;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--accent);
  background: var(--accent-soft);
  border: none;
  border-radius: 8px;
  cursor: pointer;
  margin-bottom: 1rem;
}

.result { margin-top: 1.25rem; display: none; }
.result.show { display: block; }
.result-card {
  border-radius: var(--radius);
  padding: 1rem 1.1rem;
  border: 2px solid var(--line);
}
.result-card.good { background: var(--good-bg); border-color: var(--good); }
.result-card.ok { background: #eff6ff; border-color: var(--accent); }
.result-card.close { background: var(--warn-bg); border-color: var(--warn); }
.result-card.impossible { background: var(--bad-bg); border-color: var(--bad); }
.result-card .big {
  font-size: 2rem;
  font-weight: 800;
  margin: 0.25rem 0;
}
.result-card .good .big, .result-card.good .big { color: var(--good); }
.result-card.ok .big { color: var(--accent); }
.result-card.close .big { color: var(--warn); }
.result-card.impossible .big { color: var(--bad); }
.result-card .math {
  font-size: 0.85rem;
  color: var(--muted);
  margin-top: 0.5rem;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
}
.result-card p { margin: 0.4rem 0; }

.course-row {
  display: grid;
  grid-template-columns: 1fr 5.5rem 5.5rem auto;
  gap: 0.5rem;
  align-items: end;
  margin-bottom: 0.75rem;
}
.course-row .field { margin-bottom: 0; }
.course-row .field label { font-size: 0.8rem; }
.remove-course {
  background: none;
  border: none;
  color: var(--bad);
  font-size: 1.3rem;
  cursor: pointer;
  padding: 0.4rem 0.5rem;
  line-height: 1;
}
.multi-summary { font-weight: 700; margin-bottom: 0.75rem; }
.multi-table { width: 100%; border-collapse: collapse; font-size: 0.95rem; }
.multi-table th, .multi-table td {
  text-align: left;
  padding: 0.5rem 0.4rem;
  border-bottom: 1px solid var(--line);
}
.multi-table td.num, .multi-table th.num { text-align: right; font-variant-numeric: tabular-nums; }

.faq details {
  background: #fff;
  border: 2px solid var(--line);
  border-radius: var(--radius);
  padding: 0.75rem 1rem;
  margin-bottom: 0.6rem;
}
.faq summary { font-weight: 700; cursor: pointer; }
.faq p { color: var(--ink); }

.site-footer {
  border-top: 1px solid var(--line);
  padding: 1.5rem 1rem;
  text-align: center;
  color: var(--muted);
  font-size: 0.85rem;
}

@media (max-width: 480px) {
  .course-row { grid-template-columns: 1fr 4.5rem 4.5rem auto; }
  h1 { font-size: 1.4rem; }
}