:root {
    --primary: #6366f1;
    --danger: #ef4444;
    --warning: #f59e0b;
    --success: #22c55e;
    --text: #0f172a;
    --light-bg: #f8fafc;
    --border: #e2e8f0;
  }

  * {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', system-ui, sans-serif;
  }

  body {
    background: linear-gradient(135deg, #f1f5f9, #e2e8f0);
    min-height: 100vh;
    padding: 2rem;
    color: var(--text);
  }

  .container {
    max-width: 650px;
    margin: 0 auto;
    background: white;
    border-radius: 16px;
    box-shadow: 0 10px 25px -5px rgba(0,0,0,0.1);
    padding: 2rem;
    position: relative;
    overflow: hidden;
  }

  .container::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 8px;
    background: linear-gradient(90deg, var(--primary), var(--success));
  }

  h1 {
    text-align: center;
    margin-bottom: 1.5rem;
    font-weight: 700;
    font-size: 2.2rem;
    color: var(--primary);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
  }

  h1 i {
    font-size: 1.8rem;
  }

  .input-group {
    display: flex;
    margin-bottom: 1.5rem;
    gap: 12px;
    position: relative;
  }

  .input-group input {
    flex: 1;
    padding: 14px 20px;
    font-size: 1rem;
    border: 2px solid var(--border);
    border-radius: 12px;
    transition: all 0.3s ease;
    box-shadow: 0 2px 5px rgba(0,0,0,0.05);
  }

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

  .input-group button {
    padding: 0 24px;
    background: var(--primary);
    color: white;
    border: none;
    cursor: pointer;
    border-radius: 12px;
    font-weight: 600;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    gap: 8px;
    box-shadow: 0 2px 5px rgba(99, 102, 241, 0.3);
  }

  .input-group button:hover {
    background: #4f46e5;
    transform: translateY(-1px);
  }

  .input-group button:active {
    transform: translateY(0);
  }

  .filters {
    display: flex;
    justify-content: center;
    margin-bottom: 1.5rem;
    gap: 12px;
  }

  .filters button {
    padding: 10px 20px;
    border: none;
    background: var(--light-bg);
    cursor: pointer;
    border-radius: 10px;
    font-weight: 500;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    gap: 6px;
  }

  .filters button.active {
    background: var(--primary);
    color: white;
    box-shadow: 0 2px 5px rgba(99, 102, 241, 0.3);
  }

  .filters button i {
    font-size: 0.9rem;
  }

  ul {
    list-style-type: none;
    padding: 0;
    display: flex;
    flex-direction: column;
    gap: 10px;
  }

  li {
    background: white;
    margin-bottom: 0;
    padding: 16px 20px;
    display: flex;
    align-items: center;
    border-radius: 12px;
    gap: 16px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.05);
    border: 1px solid var(--border);
    transition: all 0.3s ease;
  }

  li:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  }

  .todo-text {
    flex: 1;
    margin: 0;
    font-size: 1.05rem;
    transition: all 0.3s ease;
  }

  .todo-text.completed {
    text-decoration: line-through;
    opacity: 0.7;
  }

  .actions {
    display: flex;
    gap: 8px;
  }

  .action-btn {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.2s ease;
    border: none;
    color: white;
    font-size: 0.9rem;
  }

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

  .edit-btn {
    background: var(--warning);
  }

  .action-btn:hover {
    transform: scale(1.1);
  }

  .checkbox {
    width: 20px;
    height: 20px;
    accent-color: var(--primary);
    cursor: pointer;
    flex-shrink: 0;
  }

  .notification {
    position: fixed;
    top: 24px;
    right: 24px;
    background: var(--success);
    color: white;
    padding: 14px 24px;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
    display: flex;
    align-items: center;
    gap: 10px;
    z-index: 1000;
    transform: translateX(150%);
    transition: transform 0.3s cubic-bezier(0.68, -0.55, 0.27, 1.55);
  }

  .notification.show {
    transform: translateX(0);
  }

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

  .notification.warning {
    background: var(--warning);
  }

  .empty-state {
    text-align: center;
    color: #64748b;
    padding: 2rem;
    font-style: italic;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 12px;
  }

  .empty-state i {
    font-size: 2rem;
    opacity: 0.5;
  }

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

  .slide-in {
    animation: slideIn 0.3s ease forwards;
  }