如何在C＃中更改elemnet类的属性

Question

I have this class

.progress {

    width:200px;
    height:50px;
    border:1px solid black;
    position:relative;
}
.progress:after {

   position:absolute;
    background:black;
    top:0; bottom:0;
    left:0; 
    width:10%;
    -webkit-animation: filler 2s ease-in-out;
    -moz-animation: filler 2s ease-in-out;
    animation: filler 2s ease-in-out;
}

and have this div

<div id="percentDIV" class="progress" runat="server">some text</div>

I want to change width attribute of progress:after class in c# dynamically. Is it possible?

something like?

percentDIV.Attributes["class:progress:after"] = "width:25%";

Answer 1

Declare your next div to runat="server" and change its style

  percentDiv.Attributes["style"] = "width:20%";

Styles has precedence over classes.

Another way is to remove your class declaration from the CSS and dynamically create it on your page header section with a runat="server" control, replacing its content with your css class created dynamically.

Answer 2

percentDIV.Attributes["style"] = "width:20%";