:root {
  --primary-color: #4a6fa5;
  --primary-hover: #3a5a8f;
  --secondary-color: #6c757d;
  --success-color: #28a745;
  --danger-color: #dc3545;
  --warning-color: #ffc107;
  --info-color: #17a2b8;
  --light-color: #f8f9fa;
  --dark-color: #343a40;
  --text-color: #212529;
  --text-light: #6c757d;
  --bg-color: #ffffff;
  --bg-secondary: #f8f9fa;
  --border-color: #dee2e6;
  --shadow-color: rgba(0, 0, 0, 0.1);
  --transition-speed: 0.3s;
}
[data-theme="dark"] {
  --primary-color: #5d8acd;
  --primary-hover: #4a7bc1;
  --secondary-color: #6c757d;
  --text-color: #f8f9fa;
  --text-light: #adb5bd;
  --bg-color: #212529;
  --bg-secondary: #343a40;
  --border-color: #495057;
  --shadow-color: rgba(0, 0, 0, 0.3);
}
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
}
body {
  background-color: var(--bg-secondary);
  color: var(--text-color);
  transition: background-color var(--transition-speed) ease;
}
.app-container {
  max-width: 800px;
  margin: 0 auto;
  padding: 20px;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}
.app-header {
  margin-bottom: 30px;
  animation: fadeIn 0.5s ease;
}
.header-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 20px;
}
h1 {
  font-size: 2.5rem;
  color: var(--primary-color);
  font-weight: 700;
}
.theme-toggle button {
  background: transparent;
  border: none;
  font-size: 1.2rem;
  color: var(--text-color);
  cursor: pointer;
  padding: 5px;
  border-radius: 50%;
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background var(--transition-speed) ease;
}
.theme-toggle button:hover {
  background: var(--bg-secondary);
}
.stats-bar {
  display: flex;
  justify-content: space-around;
  background-color: var(--bg-color);
  box-shadow: 0 2px 10px var(--shadow-color);
  padding: 15px;
  margin-top: 15px;
  border-radius: 8px;
}
.stat-item {
  text-align: center;
  flex: 1;
}
.stat-count {
  display: block;
  font-size: 1.8rem;
  font-weight: bold;
  color: var(--primary-color);
}
.stat-label {
  font-size: 0.9rem;
  color: var(--text-light);
}
/* .app-main {
  flex: 1;
} */
.controls-section {
  margin-bottom: 25px;
}
.task-input-container {
  display: flex;
  gap: 10px;
  margin-bottom: 20px;
}
.task-input-container input {
  flex: 1;
  padding: 12px 15px;
  border: 1px solid var(--border-color);
  border-radius: 6px;
  font-size: 1rem;
  background-color: var(--bg-color);
  color: var(--text-color);
  transition: border-color var(--transition-speed) ease;
}
.task-input-container input:focus {
  outline: 0;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 2px rgba(74, 111, 165, 0.2);
}
.btn-primary {
  background-color: var(--primary-color);
  color: white;
  border: none;
  padding: 12px 20px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 1rem;
  font-weight: 600;
  transition: background-color var(--transition-speed) ease;
  display: flex;
  align-items: center;
  gap: 8px;
}

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

.btn-secondary {
  background-color: var(--secondary-color);
  color: white;
  border: none;
  padding: 10px 15px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 0.9rem;
  transition: background-color var(--transition-speed) ease;
}

.btn-secondary:hover {
  background-color: #5a6268;
}
.btn-icon {
  background-color: transparent;
  border: none;
  color: var(--text-light);
  cursor: pointer;
  font-size: 1rem;
  padding: 5px;
  transition: color var(--transition-speed) ease;
}
.btn-icon:hover {
  color: var(--primary-color);
}

.task-options {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 15px;
}
.task-filters {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}
.filter-select {
  padding: 8px 12px;
  border-radius: 6px;
  border: 1px solid var(--border-color);
  background-color: var(--bg-color);
  color: var(--text-color);
  font-size: 0.9rem;
  cursor: pointer;
  transition: border-color var(--transition-speed) ease;
}
.filter-select:focus {
  outline: none;
  border-color: var(--primary-color);
}

.search-container {
  display: flex;
  align-items: center;
  background-color: var(--bg-color);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  padding: 5px 10px;
  transition: border-color var(--transition-speed) ease;
}
.search-container:focus-within {
  border-color: var(--primary-color);
}

.search-container input {
  border: none;
  padding: 8px;
  font-size: 0.9rem;
  background-color: transparent;
  color: var(--text-color);
  width: 150px;
}
.search-container input:focus {
  outline: none;
}
.task-list-container {
  background-color: var(--bg-color);
  border-radius: 8px;
  box-shadow: 0 2px 10px var(--shadow-color);
  overflow: hidden;
}

.task-list {
  list-style: none;
}

/* task item */
.task-item {
  padding: 15px 20px;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  gap: 15px;
  transition: transform 0.2s ease, background-color var(--transition-speed) ease;
  cursor: grab;
}

.task-item:last-child {
  border-bottom: none;
}

.task-item:hover {
  background-color: var(--bg-secondary);
}

.task-item.dragging {
  opacity: 0.5;
  background-color: rgba(74, 111, 165, 0.1);
}

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

.task-text {
  flex: 1;
  font-size: 1rem;
  word-break: break-word;
}

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

.task-priority {
  font-size: 0.8rem;
  padding: 3px 8px;
  border-radius: 12px;
  font-weight: 600;
  text-transform: uppercase;
  margin-right: 10px;
}

.priority-high {
  background-color: rgba(220, 53, 69, 0.1);
  color: var(--danger-color);
}

.priority-medium {
  background-color: rgba(255, 193, 7, 0.1);
  color: var(--warning-color);
}

.priority-low {
  background-color: rgba(23, 162, 184, 0.1);
  color: var(--info-color);
}

.task-due-date {
  font-size: 0.8rem;
  color: var(--text-light);
  margin-right: 10px;
  display: flex;
  align-items: center;
  gap: 5px;
}

.task-due-date.overdue {
  color: var(--danger-color);
  font-weight: 600;
}

.task-category {
  font-size: 0.8rem;
  padding: 3px 8px;
  border-radius: 12px;
  background-color: rgba(40, 167, 69, 0.1);
  color: var(--success-color);
  margin-right: 10px;
}

.task-actions {
  display: flex;
  gap: 10px;
}

/* modal */
.task-details-modal {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.5);
  z-index: 1000;
  justify-content: center;
  align-items: center;
  animation: fadeIn 0.3s ease;
}
.modal-content {
  background-color: var(--bg-color);
  border-radius: 8px;
  width: 100%;
  max-width: 500px;
  padding: 25px;
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.3);
  position: relative;
}

.close-modal {
  position: absolute;
  top: 15px;
  right: 20px;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--text-light);
  transition: color var(--transition-speed) ease;
}
.close-modal:hover {
  color: var(--danger-color);
}

.modal-body {
  margin-top: 20px;
}

.form-group {
  margin-bottom: 20px;
}

.form-group label {
  display: block;
  margin-bottom: 8px;
  font-weight: 600;
  color: var(--text-color);
}

.form-control {
  width: 100%;
  padding: 10px 15px;
  border: 1px solid var(--border-color);
  border-radius: 6px;
  font-size: 1rem;
  background-color: var(--bg-color);
  color: var(--text-color);
  transition: border-color var(--transition-speed) ease;
}

.form-control:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 2px rgba(74, 111, 165, 0.2);
}

.category-input-container {
  display: flex;
  gap: 10px;
  margin-bottom: 10px;
}

.category-input-container input {
  flex: 1;
}

.category-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.category-tag {
  background-color: rgba(40, 167, 69, 0.1);
  color: var(--success-color);
  padding: 4px 10px;
  border-radius: 12px;
  font-size: 0.8rem;
  display: flex;
  align-items: center;
  gap: 5px;
}

.category-tag button {
  background: none;
  border: none;
  color: inherit;
  cursor: pointer;
  font-size: 0.7rem;
  padding: 0;
}

.modal-actions {
  display: flex;
  justify-content: flex-end;
  gap: 10px;
  margin-top: 20px;
}
.empty-state {
  text-align: center;
  padding: 40px 20px;
  color: var(--text-light);
}

.empty-state i {
  font-size: 3rem;
  margin-bottom: 20px;
  color: var(--border-color);
}

.empty-state p {
  font-size: 1.1rem;
  margin-bottom: 15px;
}
@keyframes fadeIn {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

@keyframes slideIn {
  from {
    transform: translateY(20px);
    opacity: 0;
  }
  to {
    transform: translateY(0);
    opacity: 1;
  }
}
@media (max-width: 768px) {
  .app-container {
    padding: 15px;
  }

  .task-options {
    flex-direction: column;
  }

  .task-filters {
    flex-direction: column;
  }

  .search-container {
    width: 100%;
  }

  .search-container input {
    width: 100%;
  }

  .task-item {
    flex-wrap: wrap;
  }

  .task-actions {
    margin-left: auto;
  }
}
@media (max-width: 480px) {
  h1 {
    font-size: 1.8rem;
  }

  .modal-content {
    width: 95%;
    padding: 12px;
  }

  .modal-actions {
    flex-direction: column;
  }

  .modal-actions button {
    width: 100%;
  }
}