css实现元素内容过高时自动出现展开收起按钮

1. css

.content {
    width: 600px;
    margin: 0 auto;
    max-height: 200px;
    overflow: hidden;
    border-radius: 4px;
    outline: 2px dashed royalblue;
}
.section {
    display: flex;
}
  
.content::before {
    content: '';
    width: 100px;
    height: 100%;
    float: left;
}
.btn {
    float: right;
    width: 100px;
    text-align: center;
    position: relative;
    left: calc(50% - 50px);
    transform: translateY(-100%);
    cursor: pointer;
    -webkit-tap-highlight-color: transparent;
}
.btn::after{
    content: '';
    display: block;
    height: 34px;
    background-color: #666;
    transition: .2s background-color;
    -webkit-mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 320 512'%3E %3Cpath d='M143 352.3L7 216.3c-9.4-9.4-9.4-24.6 0-33.9l22.6-22.6c9.4-9.4 24.6-9.4 33.9 0l96.4 96.4 96.4-96.4c9.4-9.4 24.6-9.4 33.9 0l22.6 22.6c9.4 9.4 9.4 24.6 0 33.9l-136 136c-9.2 9.4-24.4 9.4-33.8 0z'%3E%3C/path%3E %3C/svg%3E") center/ 24px 24px no-repeat;
}
.btn:hover::after {
    background-color: royalblue;
}
.btn::before {
    content: '';
    position: absolute;
    left: 0;
    right: 0;
    bottom: 0;
    height: 34px;
}
.text {
    box-sizing: border-box;
    width: 100%;
    padding: 10px 15px;
    float: right;
    line-height: 1.5;
    margin: 0;
    margin-left: -100px;
    font-size: 18px;
    color: #232323;
}
.checkbox:checked+.content{
    max-height: fit-content;
}
.checkbox:checked+.content .btn{
    left: auto;
    right: calc(50% - 50px);
}
.checkbox:checked+.content .btn::after{
    transform: scaleY(-1);
}

2. html

{style.section}>
     style.checkbox} type="checkbox" id="c1" hidden
     {style.content}>
          {style.text}>
              hello1 

              hello2 

              hello3 

              hello4 

              hello5 

              hello6 

              hello7 

              hello8 

              hello1 

              hello2 

              hello3 

              hello4 

              hello5 

              hello6 

              hello7 

              hello8 

          
          style.btn} htmlFor="c1"