:root {
  --primary: #4f46e5;
  --primary-dark: #3730a3;
  --border: #d1d5db;
  --bg-soft: #f8f9fc;
}

body {
  font-family: 'Segoe UI', system-ui, sans-serif;
  background: var(--bg-soft);
  color: #1f2937;
}

.navbar-brand { font-weight: 700; color: var(--primary) !important; }

.card { border: 1px solid var(--border); border-radius: 10px; }
.card-header { background: #fff; font-weight: 600; border-bottom: 1px solid var(--border); }

.btn-primary { background: var(--primary); border-color: var(--primary); }
.btn-primary:hover { background: var(--primary-dark); border-color: var(--primary-dark); }

.subject-pick {
  cursor: pointer;
  border: 2px solid var(--border);
  border-radius: 10px;
  padding: 1rem;
  text-align: center;
  transition: 0.15s;
}
.subject-pick.active,
.subject-pick:hover { border-color: var(--primary); background: #eef2ff; }
.subject-pick i { font-size: 1.8rem; color: var(--primary); }

/* ---------------- Worksheet print layout ---------------- */
.worksheet-page {
  background: #fff;
  max-width: 850px;
  margin: 20px auto;
  padding: 40px 50px;
  border: 1px solid var(--border);
  border-radius: 6px;
}
.worksheet-page.ws-a5 {
  max-width: 600px;
  padding: 28px 34px;
  font-size: 0.92rem;
}
.worksheet-page.ws-a5 .ws-header h1 { font-size: 1.3rem; }
.worksheet-page.ws-a5 .column-grid { grid-template-columns: repeat(2, 1fr); }
.ws-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  border-bottom: 3px solid #1f2937;
  padding-bottom: 12px;
  margin-bottom: 18px;
}
.ws-header h1 { font-size: 1.6rem; margin: 0; }
.ws-header .meta { font-size: 0.85rem; color: #6b7280; }
.ws-fields { display: flex; gap: 30px; margin: 14px 0 24px; font-size: 0.95rem; }
.ws-fields span { border-bottom: 1px solid #333; padding: 2px 6px; min-width: 160px; display: inline-block; }
.ws-instructions {
  background: #f3f4f6;
  border-left: 4px solid var(--primary);
  padding: 10px 14px;
  font-size: 0.9rem;
  margin-bottom: 22px;
}
.question-list { list-style: none; padding: 0; margin: 0; counter-reset: q; }
.question-item {
  padding: 12px 0;
  border-bottom: 1px dashed #e5e7eb;
  font-size: 1.02rem;
}
.question-item .q-num { font-weight: 700; margin-right: 8px; color: var(--primary-dark); }
.q-options { display: flex; flex-wrap: wrap; gap: 18px; margin-top: 6px; padding-left: 26px; font-size: 0.95rem; }
.answer-space { display: inline-block; min-width: 100px; border-bottom: 1px solid #333; margin-left: 6px; }

/* ---------------- Column-format math (stacked digits) ---------------- */
.column-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px 20px;
  margin-bottom: 20px;
}
.col-item {
  position: relative;
  padding-left: 26px;
}
.col-letter {
  position: absolute;
  left: 0;
  top: 2px;
  font-weight: 600;
  color: var(--primary-dark);
  font-size: 0.95rem;
}
.col-stack {
  font-family: 'Courier New', Courier, monospace;
  font-size: 1.4rem;
  text-align: right;
  width: 110px;
  border-bottom: 2.5px solid #1f2937;
  padding-bottom: 4px;
}
.col-num { line-height: 1.3; }
.col-op-row { display: flex; justify-content: space-between; }
.col-op { font-weight: 700; }
.col-answer-line { width: 110px; height: 30px; }

.answer-key {
  page-break-before: always;
  margin-top: 30px;
  border-top: 3px double #1f2937;
  padding-top: 16px;
}
.answer-key h2 { font-size: 1.2rem; }
.answer-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 8px 20px; font-size: 0.92rem; }

.no-print { }
@media print {
  body { background: #fff; }
  .no-print { display: none !important; }
  .no-print-badge { display: none !important; }
  .worksheet-page { border: none; margin: 0; padding: 0 10px; max-width: 100%; }
  .answer-key { page-break-before: always; }
}