CSS realizes that the left side of the webpage column is fixed and automatically adjusts the position when scrolling to the bottom

Preview address:

https://ovsexia.gitee.io/leftfixed/

html:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<script src="js/jquery-1.10.1.min.js" type="text/javascript"></script>
<link href="css/layout.css" type="text/css" rel="stylesheet" />
<link href="css/style.css" type="text/css" rel="stylesheet" />
</head>
<div class="top"></div>
<div class="page">
  <div class="left">
    <div class="left_poi"></div>
    <div class="left_in">
      <p><br />< ...
    </div><!--left_in-->
    <script>
    $(window).scroll(function()
    {
        saction();
    });
    function action()
    {
        sj = 20; //Bottom interval st = $(window).scrollTop(); //Scroll bar height sd = $(".left_poi").offset().top;
        sd_h = $(".left_in").height();
        sb = $(".bottom").offset().top;
        sb_h = $(".bottom").height();
        rd_h = $(".right").height();
        bh = window.innerHeight;
        si = sb-sd_h;
        if(st>sd && rd_h>=sd_h){
            $(".left_in").addClass("on");
            if(st>si){
                sy = bh-(sb-st)+sj;
                $(".left_in").css({"top":"auto","bottom":sy+"px"});
            }else{
                $(".left_in").css({"top":"","bottom":""});
            }
        }else{
            $(".left_in").removeClass("on");
        }
    }
    </script>
  </div><!--left-->
  <div class="right"></div>
  <div class="clear"></div>
</div><!--page-->
<div class="bottom"></div>
</body>
</html>

CSS

@charset "utf-8";
.clear {clear:both; height:0 !important; width:0 !important; overflow:hidden; font-size:0;}
.top {width:100%; height:150px; background:#0CC;}
.bottom {width:100%; height:400px; background:#39C;}
.page {width:1200px; margin:20px auto; position:relative;}
.left {width:200px; float:left;}
.left_in {width:200px; background:#46bc67; border-top:3px solid #000; border-bottom:3px solid #000;}
.left_in.on {position:fixed; top:0;}
.left_poi {width:100%; height:1px; overflow:hidden;}
.right {width:960px; height:2100px; float:right; overflow:hidden; background:#FC3;}

Summarize

The above is the CSS that I introduced to you. How to fix the left side of the web page column and automatically adjust the position when scrolling to the bottom. I hope it will be helpful to you. If you have any questions, please leave me a message and I will reply to you in time. I would also like to thank everyone for their support of the 123WORDPRESS.COM website!

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