body {
    font-family: Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    background-color: #f0f0f0;
  }
  
  .container {
    text-align: center;
    background: white;
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
  }
  
  input {
    padding: 10px;
    width: 70%;
    margin-right: 10px;
    border: 1px solid #ccc;
    border-radius: 4px;
  }
  
  button {
    padding: 10px 15px;
    background-color: #28a745;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
  }
  
  button:hover {
    background-color: #218838;
  }
  
  ul {
    list-style: none;
    padding: 0;
  }
  
  li {
    margin: 10px 0;
    padding: 10px;
    background-color: #f8f9fa;
    border-radius: 4px;
    display: flex;
    justify-content: space-between;
    align-items: center;
  }
  
  li.completed {
    text-decoration: line-through;
    color: #6c757d;
  }