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

:root {
  --bg: #0f0f0f;
  --surface: #1a1a1a;
  --surface-hover: #252525;
  --border: #333;
  --text: #e0e0e0;
  --text-muted: #888;
  --primary: #4a9eff;
  --primary-hover: #3a8eef;
  --success: #4caf50;
  --warning: #ff9800;
  --danger: #f44336;
  --high: #f44336;
  --medium: #ff9800;
  --low: #4caf50;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
}

.container {
  max-width: 800px;
  margin: 0 auto;
  padding: 2rem 1rem;
}

header {
  text-align: center;
  margin-bottom: 2rem;
}

header h1 {
  font-size: 2rem;
  font-weight: 600;
  margin-bottom: 0.25rem;
}

.subtitle {
  color: var(--text-muted);
  font-size: 0.9rem;
}

/* Stats */
.stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1rem;
  margin-bottom: 2rem;
}

.stat {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1rem;
  text-align: center;
}

.stat-value {
  display: block;
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary);
}

.stat-label {
  font-size: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

/* Add Task Form */
.add-task {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}

.add-task input[type="text"],
.add-task textarea,
.add-task select,
.add-task input[type="date"] {
  width: 100%;
  padding: 0.75rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text);
  font-size: 1rem;
  margin-bottom: 0.75rem;
}

.add-task textarea {
  min-height: 60px;
  resize: vertical;
}

.form-row {
  display: flex;
  gap: 0.75rem;
}

.form-row select,
.form-row input[type="date"] {
  flex: 1;
  margin-bottom: 0.75rem;
}

.form-row button {
  white-space: nowrap;
}

button {
  padding: 0.75rem 1.5rem;
  background: var(--primary);
  color: white;
  border: none;
  border-radius: 6px;
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
  transition: background 0.2s;
}

button:hover {
  background: var(--primary-hover);
}

.btn-secondary {
  background: var(--surface);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background: var(--surface-hover);
}

.btn-danger {
  background: var(--danger);
}

.btn-danger:hover {
  background: #d32f2f;
}

/* Filters */
.filters {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
}

.filter-btn {
  padding: 0.5rem 1rem;
  background: var(--surface);
  border: 1px solid var(--border);
  font-size: 0.85rem;
}

.filter-btn.active {
  background: var(--primary);
  border-color: var(--primary);
}

/* Tasks */
.tasks {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.task {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1rem;
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  transition: border-color 0.2s;
}

.task:hover {
  border-color: var(--primary);
}

.task.done {
  opacity: 0.6;
}

.task.done .task-title {
  text-decoration: line-through;
}

.task-checkbox {
  width: 24px;
  height: 24px;
  border: 2px solid var(--border);
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  transition: all 0.2s;
}

.task-checkbox:hover {
  border-color: var(--primary);
}

.task.done .task-checkbox {
  background: var(--success);
  border-color: var(--success);
}

.task.done .task-checkbox::after {
  content: '✓';
  color: white;
  font-size: 14px;
}

.task-content {
  flex: 1;
  min-width: 0;
}

.task-header {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 0.25rem;
}

.task-title {
  font-weight: 500;
  cursor: pointer;
}

.task-title:hover {
  color: var(--primary);
}

.priority-badge {
  font-size: 0.7rem;
  padding: 0.15rem 0.5rem;
  border-radius: 4px;
  text-transform: uppercase;
  font-weight: 600;
}

.priority-high {
  background: rgba(244, 67, 54, 0.2);
  color: var(--high);
}

.priority-medium {
  background: rgba(255, 152, 0, 0.2);
  color: var(--medium);
}

.priority-low {
  background: rgba(76, 175, 80, 0.2);
  color: var(--low);
}

.task-description {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

.task-meta {
  display: flex;
  gap: 1rem;
  font-size: 0.75rem;
  color: var(--text-muted);
}

.task-actions {
  display: flex;
  gap: 0.5rem;
  flex-shrink: 0;
}

.task-actions button {
  padding: 0.4rem 0.75rem;
  font-size: 0.8rem;
}

.timer-btn {
  background: var(--success);
}

.timer-btn.running {
  background: var(--warning);
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.7; }
}

/* Modal */
.modal {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.8);
  align-items: center;
  justify-content: center;
  z-index: 1000;
}

.modal.active {
  display: flex;
}

.modal-content {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 2rem;
  width: 90%;
  max-width: 500px;
}

.modal-content h2 {
  margin-bottom: 1.5rem;
}

.modal-content input,
.modal-content textarea,
.modal-content select {
  width: 100%;
  padding: 0.75rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text);
  font-size: 1rem;
  margin-bottom: 0.75rem;
}

.modal-actions {
  display: flex;
  gap: 0.75rem;
  justify-content: flex-end;
  margin-top: 1rem;
}

/* Empty state */
.empty-state {
  text-align: center;
  padding: 3rem;
  color: var(--text-muted);
}

/* Responsive */
@media (max-width: 600px) {
  .stats {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .form-row {
    flex-direction: column;
  }
  
  .task {
    flex-direction: column;
  }
  
  .task-actions {
    width: 100%;
    justify-content: flex-end;
  }
}