:root {
  --bg-color: #ffffff;
  --surface-color: #f9f9fb;
  --text-primary: #1a1a1a;
  --text-secondary: #666666;
  --border-color: #e5e5e5;
  --accent-color: rgb(92, 92, 255);
  --accent-hover: rgb(72, 72, 235);
  --accent-light: rgba(92, 92, 255, 0.1);
  --danger-color: #e03131;
  --success-color: #2b8a3e;
  
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
  
  --spacing-1: 4px;
  --spacing-2: 8px;
  --spacing-3: 12px;
  --spacing-4: 16px;
  --spacing-5: 24px;
  --spacing-6: 32px;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: system-ui, -apple-system, sans-serif;
  background-color: var(--surface-color);
  color: var(--text-primary);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

.app-container {
  max-width: 600px;
  margin: 0 auto;
  padding: var(--spacing-5) var(--spacing-4);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-5);
}

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

.title {
  font-size: 24px;
  font-weight: 600;
  letter-spacing: -0.02em;
}

.subtitle {
  color: var(--text-secondary);
  font-size: 14px;
  margin-top: var(--spacing-1);
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
  transition: all 0.2s cubic-bezier(0.075, 0.82, 0.165, 1);
}

button:focus-visible {
  outline: 2px solid var(--accent-color);
  outline-offset: 2px;
}

.primary-btn {
  background-color: var(--accent-color);
  color: white;
  padding: var(--spacing-2) var(--spacing-4);
  border-radius: var(--radius-md);
  font-size: 14px;
  font-weight: 500;
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-2);
  box-shadow: inset 0 1px 0 rgba(255,255,255,0.2);
}

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

.secondary-btn {
  background-color: transparent;
  color: var(--text-secondary);
  padding: var(--spacing-2) var(--spacing-4);
  border-radius: var(--radius-md);
  font-size: 14px;
  font-weight: 500;
}

.secondary-btn:hover {
  background-color: rgba(0,0,0,0.05);
  color: var(--text-primary);
}

.icon-btn {
  padding: var(--spacing-2);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  justify-content: center;
}

.icon-btn:hover {
  background-color: rgba(0,0,0,0.05);
  color: var(--text-primary);
}

.week-navigation {
  display: flex;
  align-items: center;
  gap: var(--spacing-2);
  background: var(--bg-color);
  padding: var(--spacing-2);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-color);
}

.week-days {
  display: flex;
  flex: 1;
  justify-content: space-between;
}

.day-col {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--spacing-1);
  padding: var(--spacing-2);
  border-radius: var(--radius-md);
  cursor: pointer;
  flex: 1;
}

.day-col:hover {
  background-color: var(--surface-color);
}

.day-col.active {
  background-color: var(--accent-light);
}

.day-col.active .day-date {
  color: var(--accent-color);
  font-weight: 600;
}

.day-name {
  font-size: 12px;
  color: var(--text-secondary);
  text-transform: uppercase;
}

.day-date {
  font-size: 14px;
  font-weight: 500;
}

.progress-section {
  background: var(--bg-color);
  padding: var(--spacing-4);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-color);
}

.progress-header {
  display: flex;
  justify-content: space-between;
  margin-bottom: var(--spacing-3);
  font-size: 14px;
  font-weight: 500;
}

.progress-value {
  color: var(--accent-color);
  font-variant-numeric: tabular-nums;
}

.progress-bar-container {
  height: 8px;
  background-color: var(--surface-color);
  border-radius: 4px;
  overflow: hidden;
}

.progress-bar {
  height: 100%;
  background-color: var(--accent-color);
  width: 0%;
  transition: width 0.3s cubic-bezier(0.075, 0.82, 0.165, 1);
}

.habits-list {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-3);
}

.habit-card {
  background: var(--bg-color);
  padding: var(--spacing-4);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  gap: var(--spacing-4);
  transition: transform 0.2s, box-shadow 0.2s;
}

.habit-info {
  flex: 1;
  min-width: 0;
}

.habit-name {
  font-weight: 500;
  font-size: 16px;
  margin-bottom: var(--spacing-1);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.habit-streak {
  font-size: 12px;
  color: var(--text-secondary);
}

.check-btn {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  border: 2px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: center;
  color: transparent;
  flex-shrink: 0;
}

.check-btn.checked {
  background-color: var(--accent-color);
  border-color: var(--accent-color);
  color: white;
}

.delete-btn {
  color: var(--text-secondary);
  opacity: 0;
}

.habit-card:hover .delete-btn {
  opacity: 1;
}

.delete-btn:hover {
  color: var(--danger-color);
}

.empty-state {
  text-align: center;
  padding: var(--spacing-6) 0;
  color: var(--text-secondary);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--spacing-3);
}

.empty-state[hidden] {
  display: none;
}

.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.4);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-4);
  z-index: 100;
  opacity: 1;
  transition: opacity 0.2s;
}

.modal-overlay[hidden] {
  display: none;
  opacity: 0;
}

.modal {
  background: var(--bg-color);
  padding: var(--spacing-5);
  border-radius: var(--radius-lg);
  width: 100%;
  max-width: 400px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.1);
  transform: translateY(0);
  transition: transform 0.3s cubic-bezier(0.075, 0.82, 0.165, 1);
}

.modal h2 {
  font-size: 18px;
  margin-bottom: var(--spacing-4);
}

.form-group {
  margin-bottom: var(--spacing-5);
}

.form-group label {
  display: block;
  font-size: 14px;
  font-weight: 500;
  margin-bottom: var(--spacing-2);
}

.form-group input {
  width: 100%;
  padding: var(--spacing-3);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  font-size: 16px;
  font-family: inherit;
}

.form-group input:focus {
  outline: none;
  border-color: var(--accent-color);
  box-shadow: 0 0 0 3px var(--accent-light);
}

.form-actions {
  display: flex;
  justify-content: flex-end;
  gap: var(--spacing-2);
}

@media (max-width: 480px) {
  .habit-card:hover .delete-btn {
    opacity: 1;
  }
  .day-name {
    display: none;
  }
}