:root {
  /* Light theme colors */
  --bg: #ffffff;
  --surface: #f9f9f9;
  --on-surface: #333333;
  --primary: #6200ee;
  --primary-hover: #3700b3;
  --secondary: #03dac6;
  --danger: #b00020;
  --border: #dddddd;
  --text: #000000;
  --muted: #666666;
  --radius: 4px;
  --transition: 0.3s ease;
}

body.dark-theme {
  /* Dark theme overrides */
  --bg: #121212;
  --surface: #1e1e1e;
  --on-surface: #e0e0e0;
  --primary: #bb86fc;
  --primary-hover: #3700b3;
  --secondary: #03dac6;
  --danger: #cf6679;
  --border: #333333;
  --text: #ffffff;
  --muted: #aaaaaa;
}

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

.calendar-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 1rem;
  background: var(--bg);
  color: var(--text);
}

.calendar-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1rem;
}

.calendar-header h1 {
  margin: 0;
  font-size: 1.5rem;
  color: var(--on-surface);
}

.calendar-nav button {
  background: none;
  border: none;
  font-size: 1.2rem;
  cursor: pointer;
  padding: 0.5rem;
  color: var(--on-surface);
  transition: background var(--transition);
}

.calendar-nav button:hover {
  background: var(--surface);
  border-radius: var(--radius);
}

.calendar-grid {
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  gap: 0.5rem;
}

.calendar-cell {
  border: 1px solid var(--border);
  min-height: 80px;
  position: relative;
  padding: 0.5rem;
  background: var(--surface);
  cursor: pointer;
  transition: background var(--transition), border-color var(--transition);
}

.calendar-cell:hover {
  background: var(--primary);
  color: var(--text);
}

.calendar-cell .date-number {
  font-weight: bold;
  margin-bottom: 0.3rem;
  color: var(--on-surface);
}

.calendar-cell .events {
  margin-top: 0.2rem;
}

.event {
  display: block;
  font-size: 0.8rem;
  padding: 0.1rem 0.2rem;
  margin-bottom: 0.1rem;
  border-radius: var(--radius);
  color: #fff;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.event.low { background: #6c757d; }
.event.normal { background: #007bff; }
.event.high { background: #28a745; }
.event.critical { background: #dc3545; }

.calendar-cell.today {
  border: 2px solid var(--primary);
}

.calendar-modal {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  transition: opacity var(--transition);
}

.calendar-modal.active {
  display: flex;
}

.calendar-modal .modal-content {
  background: var(--surface);
  color: var(--text);
  padding: 1.5rem;
  border-radius: var(--radius);
  width: 90%;
  max-width: 500px;
  position: relative;
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
  transition: transform var(--transition), opacity var(--transition);
}

.calendar-modal .modal-close {
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
  background: none;
  border: none;
  font-size: 1.2rem;
  cursor: pointer;
  color: var(--text);
}

.btn {
  padding: 0.4rem 0.8rem;
  border: none;
  border-radius: var(--radius);
  cursor: pointer;
  font-size: 0.9rem;
  margin-right: 0.5rem;
  transition: background var(--transition), opacity var(--transition);
}

.btn-primary { background: var(--primary); color: #fff; }
.btn-secondary { background: var(--secondary); color: #fff; }
.btn-danger { background: var(--danger); color: #fff; }

.btn:hover { opacity: 0.9; }

#theme-toggle {
  background: var(--primary);
  color: #fff;
  border: none;
  padding: 0.4rem 0.8rem;
  border-radius: var(--radius);
  cursor: pointer;
  font-size: 0.9rem;
  transition: background var(--transition), opacity var(--transition);
}

#theme-toggle:hover { opacity: 0.9; }

@media (max-width: 768px) {
  .calendar-grid {
    grid-template-columns: repeat(4, 1fr);
  }
  .calendar-cell {
    min-height: 60px;
  }
}

@media (max-width: 480px) {
  .calendar-grid {
    grid-template-columns: repeat(3, 1fr);
  }
  .calendar-cell {
    min-height: 50px;
  }
}

.week-view {
  display: grid;
  grid-template-columns: 60px repeat(7, 1fr);
  gap: 0.5rem;
  margin-top: 1rem;
}

.time-slot {
  font-size: 0.8rem;
  text-align: right;
  padding-right: 0.5rem;
  color: var(--muted);
}

.time-grid {
  display: grid;
  grid-template-rows: repeat(48, 1fr);
  gap: 0.2rem;
}

.time-grid .time-cell {
  border: 1px solid var(--border);
  height: 30px;
  position: relative;
  background: var(--surface);
}

.time-grid .time-cell .event-block {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  bottom: 0;
  background: rgba(0,123,255,0.7);
  color: #fff;
  padding: 0.2rem;
  font-size: 0.8rem;
  border-radius: var(--radius);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}