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

:root {
  --primary-color: #667eea;
  --primary-dark: #5a6fd8;
  --secondary-color: #764ba2;
  --accent-color: #f093fb;
  --success-color: #10b981;
  --danger-color: #ef4444;
  --warning-color: #f59e0b;
  --bg-color: #f8fafc;
  --card-bg: #ffffff;
  --text-primary: #1f2937;
  --text-secondary: #6b7280;
  --border-color: #e5e7eb;
  --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

[data-theme="dark"] {
  --bg-color: #0f172a;
  --card-bg: #1e293b;
  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --border-color: #334155;
}

body {
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--secondary-color)
  );
  min-height: 100vh;
  color: var(--text-primary);
  transition: all 0.3s ease;
}

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

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

.header h1 {
  color: white;
  font-size: 2.5rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

.header p {
  color: rgba(255, 255, 255, 0.9);
  font-size: 1.1rem;
  margin-bottom: 1.5rem;
}

.theme-toggle {
  position: absolute;
  top: 0;
  right: 0;
  background: rgba(255, 255, 255, 0.2);
  border: none;
  border-radius: 50%;
  width: 50px;
  height: 50px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  transition: all 0.3s ease;
  backdrop-filter: blur(10px);
}

.theme-toggle:hover {
  background: rgba(255, 255, 255, 0.3);
  transform: scale(1.1);
}

.app-card {
  background: var(--card-bg);
  border-radius: 20px;
  padding: 2rem;
  box-shadow: var(--shadow-lg);
  backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.1);
  transition: all 0.3s ease;
}

.task-input-section {
  margin-bottom: 2rem;
}

.input-group {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin-bottom: 1rem;
}

.input-row {
  display: flex;
  gap: 1rem;
  align-items: center;
}

.task-input {
  flex: 1;
  padding: 1rem;
  border: 2px solid var(--border-color);
  border-radius: 12px;
  font-size: 1rem;
  background: var(--card-bg);
  color: var(--text-primary);
  transition: all 0.3s ease;
}

.task-input:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.date-input,
.priority-select {
  padding: 1rem;
  border: 2px solid var(--border-color);
  border-radius: 12px;
  background: var(--card-bg);
  color: var(--text-primary);
  font-size: 1rem;
  transition: all 0.3s ease;
}

.date-input:focus,
.priority-select:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.add-btn {
  padding: 1rem 2rem;
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--accent-color)
  );
  color: white;
  border: none;
  border-radius: 12px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
  min-width: 120px;
}

.add-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(102, 126, 234, 0.3);
}

.add-btn:active {
  transform: translateY(0);
}

.filters {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 2rem;
  flex-wrap: wrap;
  justify-content: center;
}

.filter-btn {
  padding: 0.75rem 1.5rem;
  border: 2px solid var(--border-color);
  background: transparent;
  color: var(--text-secondary);
  border-radius: 25px;
  cursor: pointer;
  transition: all 0.3s ease;
  font-weight: 500;
}

.filter-btn.active {
  background: var(--primary-color);
  color: white;
  border-color: var(--primary-color);
  transform: scale(1.05);
}

.filter-btn:hover:not(.active) {
  border-color: var(--primary-color);
  color: var(--primary-color);
}

.task-list {
  min-height: 200px;
}

.task-item {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 1.5rem;
  margin-bottom: 1rem;
  background: var(--bg-color);
  border-radius: 12px;
  border: 1px solid var(--border-color);
  transition: all 0.3s ease;
  animation: slideIn 0.5s ease;
  position: relative;
  overflow: hidden;
}

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

.task-item.completed {
  opacity: 0.7;
}

.task-item.completed .task-text {
  text-decoration: line-through;
  color: var(--text-secondary);
}

.task-checkbox {
  width: 20px;
  height: 20px;
  cursor: pointer;
  accent-color: var(--success-color);
}

.task-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.task-text {
  font-size: 1rem;
  font-weight: 500;
  color: var(--text-primary);
}

.task-meta {
  display: flex;
  gap: 1rem;
  align-items: center;
  flex-wrap: wrap;
}

.task-date {
  font-size: 0.875rem;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.priority-badge {
  padding: 0.25rem 0.75rem;
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
}

.priority-high {
  background: rgba(239, 68, 68, 0.1);
  color: var(--danger-color);
  border: 1px solid rgba(239, 68, 68, 0.2);
}

.priority-medium {
  background: rgba(245, 158, 11, 0.1);
  color: var(--warning-color);
  border: 1px solid rgba(245, 158, 11, 0.2);
}

.priority-low {
  background: rgba(16, 185, 129, 0.1);
  color: var(--success-color);
  border: 1px solid rgba(16, 185, 129, 0.2);
}

.delete-btn {
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--danger-color);
  padding: 0.5rem;
  border-radius: 8px;
  transition: all 0.3s ease;
}

.delete-btn:hover {
  background: rgba(239, 68, 68, 0.1);
  transform: scale(1.1);
}

.empty-state {
  text-align: center;
  padding: 3rem;
  color: var(--text-secondary);
}

.empty-state svg {
  width: 64px;
  height: 64px;
  margin-bottom: 1rem;
  opacity: 0.5;
}

.stats {
  display: flex;
  gap: 1rem;
  margin-bottom: 2rem;
  flex-wrap: wrap;
}

.stat-card {
  flex: 1;
  min-width: 120px;
  padding: 1rem;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 12px;
  text-align: center;
  backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.2);
}

.stat-number {
  font-size: 2rem;
  font-weight: 700;
  color: white;
  display: block;
}

.stat-label {
  font-size: 0.875rem;
  color: rgba(255, 255, 255, 0.8);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateY(-20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes slideOut {
  from {
    opacity: 1;
    transform: translateX(0);
  }
  to {
    opacity: 0;
    transform: translateX(100%);
  }
}

.task-item.removing {
  animation: slideOut 0.3s ease forwards;
}

@media (max-width: 768px) {
  .container {
    padding: 1rem;
  }

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

  .input-row {
    flex-direction: column;
  }

  .task-item {
    padding: 1rem;
  }

  .task-meta {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.5rem;
  }

  .stats {
    flex-direction: column;
  }

  .stat-card {
    min-width: auto;
  }
}

.drag-over {
  border: 2px dashed var(--primary-color);
  background: rgba(102, 126, 234, 0.05);
}

.dragging {
  opacity: 0.5;
  transform: rotate(5deg);
}
