CSS control div width max width/height and min width/height

In webpage production, we often need to control the div width, maximum width/height or minimum width/height. However, many friends will encounter incompatibility headaches in IE6, including me. I often encounter such problems. I searched a lot on Baidu but couldn't find a solution. I later learned about it on a forum and I would like to share with you the css3 style code. Over time, it is fully compatible with all major mainstream browsers.

* minimum width */

.min_width{min-width:300px;
/* sets max-width for IE */
_width:expression(document.body.clientWidth < 300 ? "300px" : "auto");
}

/* Maximum width */
.max_width{
max-width:600px;
/* sets max-width for IE */
_width:expression(document.body.clientWidth > 600 ? "600px" : "auto");
}

/* Minimum height*/
.min_height{
min-height:200px;
/* sets min-height for IE */
_height:expression(this.scrollHeight < 200 ? "200px" : "auto" : "auto");
}

/* Maximum and minimum width*/
.min_and_max_width{
min-width:300px;
max-width:600px;
/* sets min-width & max-width for IE */
_width: expression(
        document.body.clientWidth < 300 ? "300px" :
            ( document.body.clientWidth > 600 ? "600px" : "auto")
  );
}

/* Maximum and minimum height* /
.min_and_max_height{
min-height:200px;
max-height:400px;
/* sets min-height & max-height for IE */
_height: expression(
this.scrollHeight < 200 ? "200px" :
        ( this.scrollHeight > 400 ? "400px" : "auto")
   );
}