:root {
  --bg: #f5f6f8;
  --panel: #ffffff;
  --border: #dbe0e6;
  --text: #1f2430;
  --text-muted: #6b7280;
  --accent: #3b6fe0;
  --accent-hover: #2f5bc4;
  --accent-soft: #e8effd;
  --danger: #d9483b;
  --danger-soft: #fbe9e7;
  --success: #2f9e5b;
  --front-badge: #f0a020;
  --warning: #c9962c;
  --warning-soft: #fbf1de;
  --suit-red: #c0392b;
  --seat-empty: #eef1f5;
  --seat-filled: #ffffff;
  --radius: 8px;
  --shadow: 0 1px 2px rgba(16, 24, 40, 0.06), 0 1px 3px rgba(16, 24, 40, 0.08);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #14161c;
    --panel: #1d2028;
    --border: #2c313c;
    --text: #e7e9ee;
    --text-muted: #9aa1ac;
    --accent: #5b8cf0;
    --accent-hover: #6f9bff;
    --accent-soft: #223050;
    --danger: #ef6a5c;
    --danger-soft: #3a2220;
    --success: #4ec27f;
    --front-badge: #d99a2b;
    --warning: #d9ab3f;
    --warning-soft: #3a3120;
    --suit-red: #e0685a;
    --seat-empty: #262a34;
    --seat-filled: #232734;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.3), 0 1px 3px rgba(0, 0, 0, 0.4);
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
}

#app {
  max-width: 1400px;
  margin: 0 auto;
  padding: 20px;
}

h1, h2, h3, h4 { margin: 0 0 8px; }

button {
  font-family: inherit;
  font-size: 13px;
  cursor: pointer;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  padding: 6px 12px;
  transition: background 0.12s, border-color 0.12s;
}
button:hover { border-color: var(--accent); }
button.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: white;
}
button.primary:hover { background: var(--accent-hover); }
button.danger {
  color: var(--danger);
  border-color: var(--danger);
  background: transparent;
}
button.danger:hover { background: var(--danger-soft); }
button:disabled { opacity: 0.45; cursor: not-allowed; }
button.small { padding: 3px 8px; font-size: 12px; }

input[type="text"], input[type="number"], select, textarea {
  font-family: inherit;
  font-size: 13px;
  padding: 6px 8px;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
}
input[type="checkbox"] { accent-color: var(--accent); }
input:disabled { opacity: 0.45; cursor: not-allowed; }

.paste-box { margin-bottom: 10px; }
.paste-textarea {
  width: 100%;
  resize: vertical;
  font-family: inherit;
  margin-bottom: 8px;
}

.panel {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 16px;
}

.header-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 16px;
  flex-wrap: wrap;
}

.period-tabs {
  display: flex;
  gap: 4px;
  flex-wrap: wrap;
}
.period-tab {
  padding: 7px 14px;
  border-radius: 20px;
  border: 1px solid var(--border);
  background: var(--panel);
  cursor: pointer;
  font-size: 13px;
  color: var(--text-muted);
}
.period-tab.active {
  background: var(--accent-soft);
  border-color: var(--accent);
  color: var(--accent);
  font-weight: 600;
}
.period-tab-label-input {
  width: 90px;
}

.main-grid {
  display: grid;
  grid-template-columns: 340px 1fr;
  gap: 16px;
  align-items: start;
}

@media (max-width: 900px) {
  .main-grid { grid-template-columns: 1fr; }
}

.sidebar {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.section-title {
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--text-muted);
  font-weight: 600;
  margin-bottom: 10px;
}

.roster-list {
  max-height: 320px;
  overflow-y: auto;
  border: 1px solid var(--border);
  border-radius: 6px;
}
.roster-row {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 6px 8px;
  border-bottom: 1px solid var(--border);
  font-size: 13px;
}
.roster-row:last-child { border-bottom: none; }
.roster-row.selected { background: var(--accent-soft); }
.roster-row .name { flex: 1; }
.roster-row .front-badge {
  font-size: 10px;
  background: var(--front-badge);
  color: white;
  padding: 1px 6px;
  border-radius: 10px;
}
.roster-row button.row-delete { visibility: hidden; }
.roster-row:hover button.row-delete { visibility: visible; }
.roster-row .phone-input { width: 46px; padding: 3px 6px; font-size: 11px; }

.toolbar-row {
  display: flex;
  gap: 8px;
  margin-bottom: 10px;
  flex-wrap: wrap;
}

.hint {
  font-size: 12px;
  color: var(--text-muted);
  margin-top: 6px;
}

.constraint-list {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-top: 8px;
}
.constraint-chip {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  font-size: 12px;
  padding: 5px 8px;
  border-radius: 6px;
  border: 1px solid var(--border);
}
.constraint-chip.avoid { background: var(--danger-soft); }
.constraint-chip.must { background: var(--accent-soft); }

.layout-config-row {
  display: flex;
  gap: 12px;
  margin-bottom: 12px;
  flex-wrap: wrap;
  align-items: flex-end;
}
.field {
  display: flex;
  flex-direction: column;
  gap: 4px;
  font-size: 12px;
  color: var(--text-muted);
}
.field input { width: 70px; }
.field select { width: 130px; }

.room-grid {
  display: grid;
  gap: 14px;
  padding: 16px;
  background: var(--bg);
  border: 1px dashed var(--border);
  border-radius: 8px;
}

.table-group {
  border: 2px solid var(--border);
  border-radius: 10px;
  background: var(--panel);
  padding: 8px;
  min-height: 90px;
  position: relative;
}
.table-group.front { border-color: var(--front-badge); }
.table-group.thin { border-color: var(--warning); border-style: dashed; }
.table-group.blank { border: none; background: transparent; box-shadow: none; min-height: 0; }
.table-group.empty-slot {
  border-style: dashed;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-muted);
  font-size: 12px;
  cursor: pointer;
  background: transparent;
}
.table-group .table-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 11px;
  color: var(--text-muted);
  margin-bottom: 6px;
}
.table-group .front-tag {
  color: var(--front-badge);
  font-weight: 600;
}
.table-group .thin-tag {
  color: var(--warning);
  font-weight: 600;
  font-size: 10px;
}
.table-group .table-controls {
  display: flex;
  gap: 4px;
  align-items: center;
  flex-wrap: wrap;
  margin-bottom: 6px;
}
.table-group .table-controls input[type="number"] {
  width: 44px;
  padding: 2px 4px;
}

.seat-grid {
  display: grid;
  gap: 5px;
}
.seat {
  min-width: 0;
  min-height: 48px;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--seat-empty);
  font-size: 11px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 6px 4px 4px;
  cursor: grab;
  user-select: none;
  position: relative;
  touch-action: none;
}
.seat.filled {
  background: var(--seat-filled);
  border-color: var(--accent);
  font-weight: 500;
}
.suit-badge {
  position: absolute;
  top: 3px;
  right: 5px;
  font-size: 12px;
  font-weight: 700;
  line-height: 1;
  color: var(--text);
}
.suit-badge.red { color: var(--suit-red); }
.color-badge {
  position: absolute;
  top: 5px;
  right: 6px;
  width: 11px;
  height: 11px;
  border-radius: 50%;
  border: 1px solid rgba(0, 0, 0, 0.35);
}
.seat-name { padding-right: 14px; }
.seat-phone {
  font-size: 9px;
  color: var(--text-muted);
  margin-top: 2px;
}
.seat.conflict {
  border-color: var(--danger);
  background: var(--danger-soft);
  box-shadow: 0 0 0 1px var(--danger);
}
.seat.drag-over {
  outline: 2px solid var(--accent);
  outline-offset: 1px;
}
.seat.dragging { opacity: 0.4; }

.saved-chart-row {
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding: 8px;
  border: 1px solid var(--border);
  border-radius: 6px;
  margin-bottom: 6px;
  font-size: 12px;
}
.saved-chart-row .name-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-weight: 600;
}
.saved-chart-row .timestamps {
  color: var(--text-muted);
  font-size: 11px;
}
.saved-chart-row .actions {
  display: flex;
  gap: 6px;
  margin-top: 4px;
}

.warning-banner {
  background: var(--danger-soft);
  color: var(--danger);
  border: 1px solid var(--danger);
  border-radius: 6px;
  padding: 8px 12px;
  font-size: 12px;
  margin-bottom: 12px;
}

.empty-state {
  color: var(--text-muted);
  font-size: 13px;
  padding: 20px;
  text-align: center;
}

.checkbox-row {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
}

.legend {
  display: flex;
  gap: 14px;
  font-size: 11px;
  color: var(--text-muted);
  margin-top: 10px;
  flex-wrap: wrap;
}
.legend span { display: inline-flex; align-items: center; gap: 4px; }
.swatch { width: 10px; height: 10px; border-radius: 3px; display: inline-block; }

.backup-bar {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}
.backup-status { font-size: 12px; color: var(--text-muted); }
.backup-status.stale { color: var(--warning); font-weight: 600; }

.inline-field {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  color: var(--text-muted);
}

/* "Whiteboard / Front of Class" bar — a small orientation hint on screen, the
   big banner on paper. Sits below the room in the teacher view. */
.front-bar {
  text-align: center;
  font-size: 11px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  background: var(--seat-empty);
  border-radius: 6px;
  padding: 5px;
  margin-bottom: 8px;
}
.front-bar.bottom { margin-bottom: 0; margin-top: 8px; }

.roster-row .name-edit { flex: 1; display: flex; gap: 4px; min-width: 0; }
.roster-row .name-edit input { flex: 1; min-width: 0; padding: 3px 6px; }
.roster-row .name { cursor: text; }

.print-only { display: none; }
#print-all-container { display: none; }

@media print {
  :root {
    --text: #000 !important;
    --text-muted: #333 !important;
    --border: #999 !important;
    --seat-empty: #fff !important;
    --seat-filled: #fff !important;
    --panel: #fff !important;
    --danger: #a00 !important;
    --danger-soft: #fdeceb !important;
    --suit-red: #a00 !important;
    --warning: #8a6200 !important;
    --warning-soft: #fdf3dc !important;
    --front-badge: #b5750a !important;
  }
  body { background: #fff !important; }
  /* Hide everything except the seating chart itself. Using display:none (not
     visibility:hidden) so hidden content doesn't still reserve page space and
     push out a blank second page. */
  .header-bar, .period-tabs, .sidebar-info, .layout-panel { display: none !important; }
  #app { max-width: none; margin: 0; padding: 0; }
  .main-grid { display: block; }
  .sidebar-room { display: block; }
  .seating-chart-panel {
    border: none;
    box-shadow: none;
    padding: 0;
  }
  .seating-chart-panel .section-title,
  .seating-chart-panel .toolbar-row,
  .seating-chart-panel .warning-banner,
  .seating-chart-panel .legend {
    display: none !important;
  }
  .print-only { display: block; }
  .front-bar {
    font-size: calc(28px * var(--print-scale, 1.3)) !important;
    font-weight: 800;
    text-transform: none;
    letter-spacing: 0.02em;
    color: #000 !important;
    background: none !important;
    border-radius: 0;
    border-bottom: 3px solid #000;
    padding: 0 0 10px;
    margin: 0;
  }
  .front-bar.bottom {
    border-bottom: none;
    border-top: 3px solid #000;
    padding: 10px 0 0;
    margin-top: 18px;
  }
  .print-label {
    text-align: center;
    margin: 8px 0 18px;
    font-size: calc(20px * var(--print-scale, 1.3)) !important;
    font-weight: 700;
    color: #000;
  }
  .print-label:first-child { margin-top: 0; }
  .table-group, .seat { border-color: #000 !important; }
  .table-group.thin { border-style: solid !important; }
  .thin-tag { display: none !important; }
  .front-word { display: none !important; }
  .seat.conflict {
    border-color: #000 !important;
    background: #fff !important;
    box-shadow: none !important;
  }
  .table-group.blank { border: none !important; }
  .room-grid { background: none !important; border: none !important; }

  /* Print/saved-image text size — scaled by --print-scale (set from the
     "Print font size" picker). Base numbers here are the old screen sizes;
     "Normal" (1.3x) is already a real step up from them. !important beats the
     more-specific screen-only rules that would otherwise still apply here. */
  .table-header { font-size: calc(11px * var(--print-scale, 1.3)) !important; }
  .seat { font-size: calc(11px * var(--print-scale, 1.3)) !important; }
  .seat-phone { font-size: calc(9px * var(--print-scale, 1.3)) !important; }
  .suit-badge { font-size: calc(12px * var(--print-scale, 1.3)) !important; }
  .color-badge {
    width: calc(11px * var(--print-scale, 1.3)) !important;
    height: calc(11px * var(--print-scale, 1.3)) !important;
  }

  /* "Print All Filled Periods" swaps in a container with one page per period
     instead of the single live chart. */
  body.printing-all .seating-chart-panel { display: none !important; }
  body.printing-all #print-all-container { display: block; }
  .print-page + .print-page {
    page-break-before: always;
    break-before: page;
  }
}