怎么让图片开始相对div固定，滚动后相对屏幕固定

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        body{margin: 0 auto;}
        .head{position: relative;height: 100px;background: red;}
        .body{position: relative;height: 2000px;}
        .class02,.class03{border: 1px solid #333333;height: 100%;position: relative;}
        .class02{float: left;}
        .class02{width: 880px;}
        .class03{float: right;width: 15%;margin-right: 8%;}
        .img{display: block;width: 46px;}
        #img01{position: absolute;top: 10px;left: -55px;}
        #img{background-image: url("bb.png");display: block;width: 46px;height: 46px;}
    </style>

</head>
<body>
<div class="head"></div>
<div class="body">
    <div style="margin: 0 auto;height: 100%;width: 1240px;">
    <div class="class02">
        <div class="img" id="img01">
            <div>
                <a href="#" id="img"></a>
            </div>
        </div>
    </div>
    <div class="class03"></div>
    </div>
</div>
<script src="/js.js"></script>
</body>
</html>

function navPos(){
    var scrollTop = document.documentElement.scrollTop || window.pageYOffset || document.body.scrollTop;
    if(scrollTop>165){
      $(".art-c-side").css({"position":"fixed","top":"10px","left":"-55px"});     
      }
        else{
            $(".art-c-side").css({"position":"absolute","top":"10px","left":"-55px"});
        }
}

图片说明

类似于LOL更新详情

相对div定位，然后根据滚动高度进行其他操作,修改样式

$(document).scroll(function () {
    var scroH = $(document).scrollTop();
    if (scroH > 30) {
        $("xxx").addClass("xxx");
    } else {
        $("xxx").removeClass("xxx");
    }
})


    <style>
        body{margin: 0 auto;}
        .head{position: relative;height: 100px;background: red;}
        .body{position: relative;height: 2000px;}
        .class02,.class03{border: 1px solid #333333;height: 100%;position: relative;}
        .class02{float: left;}
        .class02{width: 880px;}
        .class03{float: right;width: 15%;margin-right: 8%;}
        .img{display: block;width: 46px;}
        #img01{position: absolute;top: 10px;left: -55px;}
        #img{background:#000;display: block;width: 46px;height: 46px;}
        #img01.online{position:fixed;top:110px;left:50%;margin-left:-675px;}
    </style>

<div class="head"></div>
<div class="body">
    <div style="margin: 0 auto;height: 100%;width: 1240px;">
    <div class="class02">
        <div class="img" id="img01">
            <div>
                <a href="#" id="img"></a>
            </div>
        </div>
    </div>
    <div class="class03"></div>
    </div>
</div>

</body>
</html>
<script>
$(document).scroll(function () {
    var scroH = $(document).scrollTop();
    if (scroH > 30) {
        $("#img01").addClass("online");
    } else {
        $("#img01").removeClass("online");
    }
})

</script>

给图片设置 position: sticky;top:10px