Because "{" and "}" and "{" and "}" in CSS conflict.
It doesn't seem to be in quotes, specifically without testing.
As a result, writing scripts in CSS is not flexible, but what if you want to write a complex script into CSS? is a problem, after testing, you can first define a function, and then in the expression call on the line, but because of the use of expression in CSS, So, you can only run in IE.
Here is an example, click on the code to run.
<textarea id="runcode95907"><! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en" "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd "> <ptml xmlns=" http://www.w3.org/1999/xhtml "> <pead> <meta http-equiv=" Content-type "Content=" Tex t/html; Charset=utf-8 "/> <title>untitled document</title> <script> ex=function () {if (Document.getel Ementbyid ("DG")!=null) {return Document.getelemntbyid ("DG"). offsetwidth; }else{return 500; }} </script> <style>. aa {height:100px; Width:expression (ex ()); Background-color: #00FF00; } </style> </pead> <body> <div class= "AA" ></div> </body> </ptml> /c0></textarea>
[Ctrl + A All SELECT Note: If the need to introduce external JS need to refresh to perform]
