body {
    font-family: 'Roboto', sans-serif;
    background-color: #f7f7f7;
    margin: 0;
    padding: 20px;
    color: #333;
    font-size:18px;
  }
  
  h2 {
    color: #555;
  }
  
  ul {
    list-style-type: none;
    padding: 0;
  }
  
  li {
    background-color: #fff;
    margin-bottom: 10px;
    padding: 15px;
    border-radius: 3px;
    box-shadow: 0 10px 10px rgba(0, 0, 0, 0.1);
  }
  


  li.completed {
    text-decoration: line-through;
    color: #aaa;
  }
  
  .task-input {
      font-size:18px;
    padding: 10px;
    margin-bottom: 20px;
    border: none;
    border-bottom: 2px solid #aaa;
    width: calc(100% - 20px);
    height:50px;
    box-sizing: border-box;
  }
  
  .add-btn {
    padding: 10px 30px;
    background-color: #28a745;
    border: none;
    border-radius: 3px;
    color: white;
    cursor: pointer;
    transition: background-color 0.3s;
    font-size:20px;
  }
  
  .add-btn:hover {
    background-color: #218838;
  }

  .add-btn:focus {
    outline: none;
  }

  .toast {
    position: fixed;
    top: 20%;
    left: 50%;
    transform: translate(-50%, -50%);
    padding: 10px 20px;
    background-color: #4ca44c;
    color: #ebeee8;
    border-radius: 5px;
    z-index: 1000;
    opacity: 0;
    animation: fadeInOut 2.5s;
  }

  @keyframes fadeInOut {
    0%, 100% {
      opacity: 0;
    }
    10%, 90% {
      opacity: 1;
    }
  }

li.completed {
text-decoration: line-through;
color: #aaa;
}

li input[type='checkbox'] {
width: 30px;
height: 30px;
margin-right: 10px;
vertical-align: middle;
cursor: pointer;
border: 1px solid #b6b6b6;
border-radius: 4px;
appearance: none;
-webkit-appearance: none;
background-color: #15e234;
}

li input[type='checkbox']:checked {
background-color: #565454;
border-color: #393636;

}
#completedCheckbox {
  filter: grayscale(1); /* 将勾选框变成灰色 */