CSS is simple. As a web developer, we can do the styling by creating a css file. However, some might have faced the problem of styling pages in a dynamic manner. Example, if you want the CSS to display differently when different people logs in. Or you want to programmatically change it depending on which day it is on.

In this article, I will try my best to explain it in 3 simple steps.  :)

Step 1: Create an aspx file, let's name it as "DynamicCss.aspx". Remove the additional script and leave the script as below sample code.

<%@ Page Language="VB" AutoEventWireup="false"
CodeFile="DynamicCss.aspx.vb" Inherits="DynamicCss" %>
<asp:Literal ID="ltlDynamicCSS" runat="server" />

Step 2: Generate the css script from its code behind with the QueryString values. (considering you have done all the validation with the Query String value before used)

Dim sbDynamicCss As New StringBuilder

With sbDynamicCss
            ' General style
           .Append(".msg { padding:3px; color:#" & Request.QueryString("color").ToString & "; } ")
           .Append(".pointer { cursor: pointer; } ")
           .Append(".common { font-size: 8pt; font-family: Verdana; } ")
End With
Me.ltlDynamicCSS.Text = sbDynamicCss.ToString

Step 3: Create another aspx file as "Default.aspx". Normally we includes a htmllink from html header tag. For this case, I will generate htmllink from code behind when page load. This is much more flexible that you may send in the attribute value using query string.

Dim csslink As New HtmlLink
csslink.Attributes.Add("type", "text/css")
csslink.Attributes.Add("rel", "stylesheet")
csslink.Attributes.Add("href", "DynamicCss.aspx?color=#f0f0f0")
Me.Head1.Controls.Add(csslink)

That's all! You have generated a dynamic css. Of course you got to assign a css class to a control from the Default.aspx file. For example:

<div id="div1" class="msg">Hello World</div>