body{
    font-family: "Microsoft YaHei", sans-serif;
}

.container{
    background-color: #f5f5f5;
    position: fixed;
    left: 0px;
    top: 0px;
    height: 100%;
    width: 100%;
    display: flex;
    justify-content: center;
    align-items: center;

}

.collapse-item{
    position: relative;
}

.collapse-item input{
    position: absolute;
    visibility: hidden;
}

.collapse-item-title{
    cursor: pointer;
    padding-left: 8px;
    padding-right: 8px;
    color: white;
    background-color: #4b4b4b;
    width: 150px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.collapse-item-title i{
    transform: rotate(0deg);
    transition: transform 0.4s;
}

.collapse-item-list{
    height: 0px;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.6s;
}

.collapse-item input:checked + .collapse-item-title i{
    transform: rotate(-90deg);
}

.collapse-item input:checked + .collapse-item-title + .collapse-item-list{
    height: auto;
    opacity: 1;
    visibility: visible;
}

.collapse-item-list div{
    background-color: #4daf7c;
    color: white;
    padding: 8px;
    cursor: pointer;
    text-align: center;
    font-size: 14px;
    transition: background-color 0.4s;

}

.collapse-item-list div:hover{
    background-color: #2ED07D;
}