:root {
  --primary-color: #6366f1;
  --primary-hover: #4f46e5;
  --low-priority: #10b981;
  --medium-priority: #f59e0b;
  --high-priority: #ef4444;
  --text-primary: #1f2937;
  --text-secondary: #6b7280;
  --bg-primary: #ffffff;
  --bg-secondary: #f9fafb;
  --border-color: #e5e7eb;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --radius-sm: 0.25rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --transition: all 0.3s ease;
}

.dark-theme {
  --primary-color: #818cf8;
  --primary-hover: #6366f1;
  --text-primary: #f9fafb;
  --text-secondary: #9ca3af;
  --bg-primary: #1f2937;
  --bg-secondary: #111827;
  --border-color: #374151;
}

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

body {
  font-family: 'Inter', sans-serif;
  background-color: var(--bg-secondary);
  color: var(--text-primary);
  min-height: 100vh;
  transition: var(--transition);
}

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

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 2rem;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.logo i {
  font-size: 1.75rem;
  color: var(--primary-color);
}

.logo h1 {
  font-weight: 700;
  font-size: 1.75rem;
  background: linear-gradient(90deg, var(--primary-color), #8b5cf6);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.theme-toggle {
  cursor: pointer;
  padding: 0.5rem;
  border-radius: 50%;
  background-color: var(--bg-primary);
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

.theme-toggle:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.stats-banner {
  display: flex;
  justify-content: space-between;
  margin-bottom: 2rem;
  background-color: var(--bg-primary);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  box-shadow: var(--shadow-md);
}

.stat-item {
  text-align: center;
}

.stat-item span {
  display: block;
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary-color);
  margin-bottom: 0.25rem;
}

.stat-item p {
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.search-container {
  position: relative;
  margin-bottom: 1.5rem;
}

.search-container i {
  position: absolute;
  left: 1rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-secondary);
}

#search {
  width: 100%;
  padding: 1rem 1rem 1rem 3rem;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  font-size: 1rem;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

#search:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

.filter-container {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
  overflow-x: auto;
  padding-bottom: 0.5rem;
}

.filter-btn {
  padding: 0.5rem 1rem;
  background-color: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
  cursor: pointer;
  transition: var(--transition);
  white-space: nowrap;
}

.filter-btn:hover {
  background-color: var(--bg-secondary);
}

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

.tasks-container {
  background-color: var(--bg-primary);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
  min-height: 300px;
  position: relative;
}

#tasks-list {
  list-style-type: none;
}

.task-item {
  display: flex;
  align-items: center;
  padding: 1rem;
  border-radius: var(--radius-md);
  margin-bottom: 0.5rem;
  background-color: var(--bg-secondary);
  transition: var(--transition);
  animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.task-item:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}

.task-checkbox {
  margin-right: 1rem;
  appearance: none;
  width: 20px;
  height: 20px;
  border: 2px solid var(--border-color);
  border-radius: 50%;
  cursor: pointer;
  position: relative;
  transition: var(--transition);
}

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

.task-checkbox:checked::after {
  content: '✓';
  position: absolute;
  color: white;
  font-size: 12px;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

.task-content {
  flex-grow: 1;
  transition: var(--transition);
}

.task-text {
  font-size: 1rem;
  margin-bottom: 0.25rem;
  transition: var(--transition);
}

.task-date {
  font-size: 0.75rem;
  color: var(--text-secondary);
}

.task-checkbox:checked + .task-content .task-text {
  text-decoration: line-through;
  color: var(--text-secondary);
}

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

.task-btn {
  background: none;
  border: none;
  font-size: 0.875rem;
  color: var(--text-secondary);
  cursor: pointer;
  padding: 0.25rem;
  border-radius: var(--radius-sm);
  transition: var(--transition);
}

.task-btn:hover {
  color: var(--primary-color);
  background-color: rgba(99, 102, 241, 0.1);
}

.task-priority {
  display: flex;
  align-items: center;
  margin-right: 1rem;
}

.priority-indicator {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  margin-right: 0.5rem;
}

.priority-low {
  background-color: var(--low-priority);
}

.priority-medium {
  background-color: var(--medium-priority);
}

.priority-high {
  background-color: var(--high-priority);
}

.empty-state {
  text-align: center;
  padding: 2rem 0;
  color: var(--text-secondary);
  display: none;
}

.empty-image {
  max-width: 200px;
  margin-bottom: 1rem;
  opacity: 0.7;
}

.add-task-container {
  display: flex;
  margin-bottom: 1.5rem;
  gap: 0.75rem;
}

#new-task {
  flex-grow: 1;
  padding: 1rem;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  font-size: 1rem;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  box-shadow: var(--shadow-sm);
}

#new-task:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

.priority-selector {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0 0.75rem;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  background-color: var(--bg-primary);
}

.priority-dot {
  width: 16px;
  height: 16px;
  border-radius: 50%;
  cursor: pointer;
  transition: var(--transition);
  opacity: 0.4;
}

.priority-dot.active {
  opacity: 1;
  transform: scale(1.2);
}

.priority-dot.low {
  background-color: var(--low-priority);
}

.priority-dot.medium {
  background-color: var(--medium-priority);
}

.priority-dot.high {
  background-color: var(--high-priority);
}

#add-task {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0 1.5rem;
  border: none;
  border-radius: var(--radius-lg);
  background-color: var(--primary-color);
  color: white;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
  box-shadow: var(--shadow-sm);
}

#add-task:hover {
  background-color: var(--primary-hover);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

footer {
  text-align: center;
  padding: 1.5rem;
  color: var(--text-secondary);
  font-size: 0.875rem;
}

footer i {
  color: var(--high-priority);
}

@media (max-width: 640px) {
  .app-container {
    padding: 1rem;
  }

  .stats-banner {
    flex-direction: column;
    gap: 1rem;
  }

  .add-task-container {
    flex-direction: column;
  }
  
  #add-task {
    width: 100%;
    justify-content: center;
    padding: 1rem;
  }
  
  .priority-selector {
    justify-content: center;
    padding: 0.75rem;
  }
}