:root {
  color-scheme: light;
  font-family: Inter, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --bg: #fafafa;
  --surface: #ffffff;
  --border: #d8d8d8;
  --text: #1f2937;
  --muted: #6b7280;
  --primary: #10b981;
  --primary-strong: #047857;
  --danger: #ef4444;
}

* {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  min-height: 100%;
  background: var(--bg);
  color: var(--text);
}

body {
  padding: 24px;
}

.app-shell {
  max-width: 800px;
  margin: 0 auto;
  display: grid;
  gap: 24px;
}

.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.app-header h1 {
  margin: 0;
  font-size: 2rem;
}

.app-header p {
  margin: 4px 0 0;
  color: var(--muted);
}

.nav-buttons {
  display: flex;
  gap: 12px;
}

button {
  border: 1px solid var(--border);
  background: white;
  color: var(--text);
  padding: 10px 16px;
  border-radius: 12px;
  cursor: pointer;
  font: inherit;
  transition: transform 0.12s ease, border-color 0.12s ease, background-color 0.12s ease;
}

button:hover {
  background: #f4f4f4;
}

button:active {
  transform: translateY(1px);
}

button.secondary {
  border-color: transparent;
  background: #f3f4f6;
}

.calendar-card, .note-panel, .diary-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 24px;
  padding: 24px;
}

.diary-actions {
  display: flex;
  gap: 12px;
  margin-bottom: 16px;
}

.diary-actions input {
  flex: 1;
  padding: 10px 14px;
  border: 1px solid var(--border);
  border-radius: 14px;
  font: inherit;
}

.diary-list {
  display: grid;
  gap: 10px;
}

.diary-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 14px 16px;
  border-radius: 18px;
  background: #f8fafc;
}

.diary-item button {
  padding: 8px 14px;
}

.diary-empty {
  color: var(--muted);
}

.month-header {
  display: flex;
  justify-content: center;
  margin-bottom: 16px;
}

.month-header span {
  font-size: 1.25rem;
  font-weight: 700;
}

.weekdays,
.calendar-grid {
  display: grid;
  grid-template-columns: repeat(7, minmax(0, 1fr));
  gap: 10px;
}

.weekdays span {
  text-align: center;
  color: var(--muted);
  font-size: 0.9rem;
}

.day-cell {
  min-height: 76px;
  border-radius: 18px;
  background: #f8fafc;
  border: 1px solid transparent;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  padding: 12px;
  cursor: pointer;
  transition: border-color 0.15s ease, background-color 0.15s ease;
}

.day-cell.empty {
  background: transparent;
  cursor: default;
}

.day-cell:hover:not(.empty) {
  background: #eef2ff;
}

.day-label {
  font-weight: 700;
}

.day-cell.note {
  background: #ecfdf5;
}

.day-cell.note .day-label {
  color: var(--primary-strong);
}

.day-cell.today {
  background: #fef3c7;
  border-color: #fbbf24;
}

.day-cell.today .day-label {
  color: #92400e;
}

.day-cell.today.note {
  background: #fef3c7;
  border-color: #f59e0b;
}

.day-cell.today.note .day-label {
  color: #92400e;
}

.day-cell.selected {
  border-color: #000000;
}

.note-indicator {
  width: 12px;
  height: 12px;
  border-radius: 999px;
  background: var(--primary);
  margin-top: 8px;
  justify-self: end;
}

.note-panel.hidden {
  display: none;
}

.note-panel-header {
  margin-bottom: 12px;
}

#noteText {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 16px;
  font: inherit;
  resize: vertical;
  min-height: 180px;
}

.note-actions {
  margin-top: 16px;
  display: flex;
  gap: 12px;
}

button.danger {
  border-color: #f87171;
  background: #fee2e2;
  color: #991b1b;
}

button.danger:hover {
  background: #fecaca;
}

@media (max-width: 640px) {
  body {
    padding: 16px;
  }

  .app-header {
    flex-direction: column;
    align-items: stretch;
  }

  .calendar-card, .note-panel {
    padding: 18px;
  }
}