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

:root {
  --primary-color: #4f46e5;
  --primary-hover: #4338ca;
  --secondary-color: #64748b;
  --success-color: #10b981;
  --warning-color: #f59e0b;
  --danger-color: #ef4444;
  --bg-color: #f8fafc;
  --sidebar-bg: #1e293b;
  --sidebar-text: #e2e8f0;
  --card-bg: #ffffff;
  --text-primary: #1e293b;
  --text-secondary: #64748b;
  --border-color: #e2e8f0;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 40px rgba(0, 0, 0, 0.1);
  --radius: 8px;
  --transition: all 0.3s ease;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background-color: var(--bg-color);
  color: var(--text-primary);
  line-height: 1.6;
}

.app-container {
  display: flex;
  min-height: 100vh;
}

/* 侧边栏样式 */
.sidebar {
  width: 240px;
  background: var(--sidebar-bg);
  color: var(--sidebar-text);
  display: flex;
  flex-direction: column;
  position: fixed;
  height: 100vh;
  left: 0;
  top: 0;
  z-index: 100;
}

.logo {
  padding: 24px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.logo h1 {
  font-size: 1.25rem;
  font-weight: 600;
}

.nav-menu {
  flex: 1;
  padding: 16px 0;
}

.nav-item {
  display: flex;
  align-items: center;
  gap: 12px;
  width: 100%;
  padding: 12px 24px;
  border: none;
  background: transparent;
  color: var(--sidebar-text);
  font-size: 0.95rem;
  cursor: pointer;
  transition: var(--transition);
  text-align: left;
}

.nav-item:hover {
  background: rgba(255, 255, 255, 0.1);
}

.nav-item.active {
  background: var(--primary-color);
  color: white;
}

.nav-item .icon {
  font-size: 1.2rem;
}

.sidebar-footer {
  padding: 16px 24px;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  font-size: 0.75rem;
  color: var(--secondary-color);
}

/* 主内容区 */
.main-content {
  flex: 1;
  margin-left: 240px;
  padding: 24px;
  min-height: 100vh;
}

.view {
  display: none;
}

.view.active {
  display: block;
  animation: fadeIn 0.3s ease;
}

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

.view-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 24px;
}

.view-header h2 {
  font-size: 1.5rem;
  font-weight: 600;
}

/* 按钮样式 */
.btn {
  padding: 10px 20px;
  border: none;
  border-radius: var(--radius);
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
}

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

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

.btn-secondary {
  background: var(--border-color);
  color: var(--text-primary);
}

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

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

.btn-danger:hover {
  background: #dc2626;
}

.btn-sm {
  padding: 6px 12px;
  font-size: 0.8rem;
}

/* 笔记卡片 */
.notes-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 20px;
}

.note-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow);
  cursor: pointer;
  transition: var(--transition);
  border: 1px solid transparent;
}

.note-card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
  border-color: var(--primary-color);
}

.note-card-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 12px;
}

.note-card h3 {
  font-size: 1.1rem;
  font-weight: 600;
  word-break: break-word;
}

.note-card .category-badge {
  padding: 4px 10px;
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 500;
  white-space: nowrap;
}

.category-general { background: #e0e7ff; color: #4338ca; }
.category-work { background: #dcfce7; color: #166534; }
.category-personal { background: #fef3c7; color: #92400e; }
.category-ideas { background: #fce7f3; color: #9d174d; }

.note-card p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
  margin-bottom: 12px;
}

.note-card-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.8rem;
  color: var(--secondary-color);
}

/* 待办列表 */
.todo-filters {
  display: flex;
  gap: 8px;
}

.filter-btn {
  padding: 8px 16px;
  border: 1px solid var(--border-color);
  background: var(--card-bg);
  border-radius: var(--radius);
  font-size: 0.85rem;
  cursor: pointer;
  transition: var(--transition);
}

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

.todo-input-container {
  display: flex;
  gap: 12px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}

.todo-input-container input[type="text"] {
  flex: 1;
  min-width: 200px;
  padding: 12px 16px;
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  font-size: 0.95rem;
  transition: var(--transition);
}

.todo-input-container input[type="text"]:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

.todo-input-container select,
.todo-input-container input[type="date"] {
  padding: 12px 16px;
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  font-size: 0.95rem;
  background: var(--card-bg);
}

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

.todo-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 16px;
  background: var(--card-bg);
  border-radius: var(--radius);
  margin-bottom: 8px;
  box-shadow: var(--shadow);
  transition: var(--transition);
}

.todo-item:hover {
  box-shadow: var(--shadow-lg);
}

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

.todo-checkbox {
  width: 22px;
  height: 22px;
  border: 2px solid var(--border-color);
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
  flex-shrink: 0;
}

.todo-checkbox:hover {
  border-color: var(--success-color);
}

.todo-checkbox.checked {
  background: var(--success-color);
  border-color: var(--success-color);
}

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

.todo-text {
  flex: 1;
  font-size: 0.95rem;
}

.todo-priority {
  padding: 4px 8px;
  border-radius: 4px;
  font-size: 0.75rem;
  font-weight: 500;
}

.priority-low { background: #dcfce7; color: #166534; }
.priority-normal { background: #e0e7ff; color: #4338ca; }
.priority-high { background: #fef2f2; color: #991b1b; }

.todo-due-date {
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.todo-actions {
  display: flex;
  gap: 8px;
  opacity: 0;
  transition: var(--transition);
}

.todo-item:hover .todo-actions {
  opacity: 1;
}

.icon-btn {
  width: 32px;
  height: 32px;
  border: none;
  background: transparent;
  border-radius: var(--radius);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
}

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

.icon-btn.delete:hover {
  background: #fef2f2;
  color: var(--danger-color);
}

/* 统计页面 */
.stats-container {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 20px;
  margin-top: 20px;
}

.stat-card {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 24px;
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.stat-icon {
  font-size: 2.5rem;
}

.stat-info {
  display: flex;
  flex-direction: column;
}

.stat-number {
  font-size: 2rem;
  font-weight: 700;
  color: var(--primary-color);
}

.stat-label {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

/* 模态框 */
.modal {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.5);
  z-index: 1000;
  align-items: center;
  justify-content: center;
  animation: fadeIn 0.2s ease;
}

.modal.active {
  display: flex;
}

.modal-content {
  background: var(--card-bg);
  border-radius: var(--radius);
  width: 90%;
  max-width: 600px;
  max-height: 90vh;
  overflow-y: auto;
  animation: slideUp 0.3s ease;
}

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

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 20px;
  border-bottom: 1px solid var(--border-color);
}

.modal-header h3 {
  font-size: 1.2rem;
}

.close-btn {
  width: 32px;
  height: 32px;
  border: none;
  background: transparent;
  font-size: 1.5rem;
  cursor: pointer;
  border-radius: var(--radius);
  transition: var(--transition);
}

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

.modal-body {
  padding: 20px;
}

.form-group {
  margin-bottom: 16px;
}

.form-group label {
  display: block;
  margin-bottom: 6px;
  font-weight: 500;
  font-size: 0.9rem;
}

.form-group input,
.form-group select,
.form-group textarea {
  width: 100%;
  padding: 10px 14px;
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  font-size: 0.95rem;
  transition: var(--transition);
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

.form-group textarea {
  resize: vertical;
  min-height: 150px;
}

.modal-footer {
  display: flex;
  justify-content: flex-end;
  gap: 12px;
  padding: 20px;
  border-top: 1px solid var(--border-color);
}

/* 提示消息 */
.toast {
  position: fixed;
  bottom: 24px;
  right: 24px;
  padding: 14px 24px;
  background: var(--sidebar-bg);
  color: white;
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  z-index: 2000;
  transform: translateY(100px);
  opacity: 0;
  transition: var(--transition);
}

.toast.show {
  transform: translateY(0);
  opacity: 1;
}

.toast.success {
  background: var(--success-color);
}

.toast.error {
  background: var(--danger-color);
}

/* 空状态 */
.empty-state {
  text-align: center;
  padding: 60px 20px;
  color: var(--text-secondary);
}

.empty-state .icon {
  font-size: 4rem;
  margin-bottom: 16px;
}

.empty-state h3 {
  margin-bottom: 8px;
  color: var(--text-primary);
}

/* 登录页面 */
.login-container {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  padding: 20px;
}

.login-box {
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  width: 100%;
  max-width: 400px;
  padding: 40px;
}

.login-header {
  text-align: center;
  margin-bottom: 32px;
}

.login-header h1 {
  font-size: 2rem;
  margin-bottom: 8px;
  color: var(--text-primary);
}

.login-header p {
  color: var(--text-secondary);
  font-size: 0.95rem;
}

.login-form {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.btn-block {
  width: 100%;
  padding: 12px;
  font-size: 1rem;
}

.error-message {
  color: var(--danger-color);
  font-size: 0.9rem;
  text-align: center;
  padding: 8px;
  background: #fef2f2;
  border-radius: var(--radius);
  margin-top: 8px;
}

.btn-sm {
  padding: 6px 12px;
  font-size: 0.85rem;
}

/* 响应式设计 */
@media (max-width: 768px) {
  .app-container {
    flex-direction: column;
  }

  .sidebar {
    width: 100%;
    height: auto;
    position: relative;
    flex-direction: row;
    padding: 0;
  }

  .logo {
    padding: 12px 16px;
    border-bottom: none;
    border-right: 1px solid rgba(255, 255, 255, 0.1);
  }

  .logo h1 {
    font-size: 1rem;
    white-space: nowrap;
  }

  .nav-menu {
    flex: 1;
    flex-direction: row;
    padding: 0;
    overflow-x: auto;
  }

  .nav-item {
    padding: 12px 16px;
    white-space: nowrap;
    border-right: 1px solid rgba(255, 255, 255, 0.1);
  }

  .nav-item span:not(.icon) {
    display: inline;
    margin-left: 6px;
  }

  .sidebar-footer {
    display: none;
  }

  .main-content {
    margin-left: 0;
    padding: 12px;
    width: 100%;
  }

  .view-header {
    flex-direction: column;
    gap: 12px;
    align-items: flex-start;
  }

  .view-header h2 {
    font-size: 1.25rem;
  }

  .notes-grid {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .note-card {
    padding: 16px;
  }

  .todo-filters {
    width: 100%;
    justify-content: space-between;
  }

  .filter-btn {
    flex: 1;
    text-align: center;
  }

  .todo-input-container {
    flex-direction: column;
    gap: 8px;
  }

  .todo-input-container input,
  .todo-input-container select,
  .todo-input-container button {
    width: 100%;
  }

  .todo-item {
    padding: 12px;
    flex-wrap: wrap;
  }

  .todo-actions {
    opacity: 1;
    width: 100%;
    justify-content: flex-end;
    margin-top: 8px;
  }

  .stats-container {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .stat-card {
    padding: 16px;
  }

  .modal-content {
    width: 95%;
    max-width: none;
    margin: 10px;
  }

  .modal-body {
    padding: 16px;
  }

  .modal-footer {
    padding: 16px;
    flex-direction: column;
  }

  .modal-footer .btn {
    width: 100%;
  }

  .login-box {
    padding: 24px;
  }

  .login-header h1 {
    font-size: 1.5rem;
  }
}

@media (max-width: 480px) {
  .main-content {
    padding: 8px;
  }

  .view-header h2 {
    font-size: 1.1rem;
  }

  .btn {
    padding: 8px 16px;
    font-size: 0.85rem;
  }

  .note-card h3 {
    font-size: 1rem;
  }

  .stat-icon {
    font-size: 2rem;
  }

  .stat-number {
    font-size: 1.5rem;
  }
}