li::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 0;
    width: .36rem;
    height: .36rem;
    margin-top: -.18rem;
    border-radius: .36rem;
    border: .01rem solid #279ECD;
}

li.active::before {
    background-color: #279ECD;
}

$('ul').click('click','li',function(){
    $(this).addClass("active").siblings().removeClass("active");
})