body {
  font-family: Arial, sans-serif;
  max-width: 560px;
  margin: 0 auto;
  padding: 20px;
  transition: background-color 0.3s, color 0.3s;
}
body.dark { background: #181c1f; color: #f0f0f0; }
body.light-mode { background: #f0f0f0; color: #222; }
.container { margin-top: 60px; }
h1 { text-align: center; margin-bottom: 24px; font-size: 1.5em; }
.section {
  background: #fff;
  border-radius: 12px;
  padding: 20px;
  margin-bottom: 16px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.08);
}
body.dark .section { background: #23272a; }
label { display: block; margin-bottom: 6px; }
textarea {
  width: 100%;
  box-sizing: border-box;
  padding: 10px;
  border-radius: 8px;
  border: 1px solid #ccc;
  margin-bottom: 12px;
}
body.dark textarea { background: #333; border-color: #555; color: #f0f0f0; }
button {
  padding: 10px 20px;
  border-radius: 8px;
  border: none;
  font-weight: 600;
  cursor: pointer;
  background: #1976d2;
  color: #fff;
  margin-right: 8px;
  margin-bottom: 8px;
}
body.dark button { background: #90caf9; color: #111; }
.bingo-preview-section { overflow-x: auto; }
.bingo-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 2px;
  max-width: 360px;
  margin: 0 auto;
  border: 2px solid #333;
  border-radius: 8px;
  overflow: hidden;
}
body.dark .bingo-grid { border-color: #666; }
.bingo-cell {
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 8px;
  text-align: center;
  font-size: 0.9em;
  background: #fff;
  border: 1px solid #ddd;
  cursor: pointer;
  user-select: none;
}
body.dark .bingo-cell { background: #2a2a2a; border-color: #444; }
.bingo-cell.checked { background: #c8e6c9; font-weight: bold; }
body.dark .bingo-cell.checked { background: #1b5e20; }
.bingo-cell.free { background: #fff9c4; font-weight: bold; }
body.dark .bingo-cell.free { background: #f9a825; color: #111; }
@media print {
  body * { visibility: hidden; }
  .bingo-preview-section, .bingo-preview-section * { visibility: visible; }
  .bingo-preview-section { position: absolute; left: 0; top: 0; width: 100%; }
  .bingo-cell.checked { background: #c8e6c9 !important; -webkit-print-color-adjust: exact; print-color-adjust: exact; }
  .bingo-cell.free { background: #fff9c4 !important; -webkit-print-color-adjust: exact; print-color-adjust: exact; }
}