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You're in luck today since I have the code that will get all the styles with the current page. Plus y just add to the collection or remove from the collection as you wish. 
 
In your master page simply give your &nbsp;tag an id and ensure that the runat=&quot;server&quot; is set. 
 
using the code below in the code snippet you can then remove stylesheet links from the header by using the following code: 
 
Page.Header.Controls.Remove(hlnk[i]); 

<pre><code class="code-10 nolinks" id="code-120270">List&lt;HtmlLink&gt; hlnk = new List&lt;HtmlLink&gt;();
 
// Get all styles
Control header = FindControl(&quot;masterHeader&quot;);
if (header != null)
{
	foreach (Control c in header.Controls)
	{
		if (c is HtmlLink)
			hlnk.Add(c as HtmlLink);
	}
}
</code></pre>
</div>

<div>
Looks pretty good, though I'm drawing a few blanks, mostly because I've never done anything like this before. So are you saying that &quot;HtmlLink&quot; will only pick up the stylesheet links? 
 
Not sure how that will set the .css file it uses based on the QueryString, at the moment anyway. Can you clarify a bit, please?
</div>

<div>
Yes the HtmlLink class is used to link the CSS stylesheets to the page. See <a href="http://msdn.microsoft.com/en-us/library/system.web.ui.htmlcontrols.htmllink(VS.80).aspx" rel="ugc">http://msdn.microsoft.com/en-us/library/system.web.ui.htmlcontrols.htmllink(VS.80).aspx</a>. 
 
The code I provided will identify all the CSS stylesheet within the page. Plus add or remove styles.
</div>

<div>
MonkeyPushButton- 
 
I thnk that code looks good, but the problem is when I put it in (well, massaged a bit to fit within my web app's parameters and such), I get an error : 
 
The control collection cannot be modified during DataBind, Init, Load, PreRender or Unload phases. 
 
So if that's the case, is it indeed possible to do what I'm trying to do?
</div>

<div>
Interesting. I have used that code during the OnLoad event of my master page. protected override void OnLoad(EventArgs e). 
 
When attempting to remove an element from the collection don't &nbsp;use the foreach statement, better to use for (int i = 0; i &lt;&nbsp;hlnk.Count; i++). 
 
Have a look at the code I used 

<pre><code class="code-10 nolinks" id="code-120344">protected override void OnLoad(EventArgs e)
{
	#region Add / Remove stylesheet based on browser
 
	List&lt;HtmlLink&gt; hlnk = new List&lt;HtmlLink&gt;();
 
	// Get all styles
	Control header = FindControl(&quot;masterHeader&quot;);
	if (header != null)
	{
		foreach (Control c in header.Controls)
		{
			if (c is HtmlLink)
				hlnk.Add(c as HtmlLink);
		}
 
		for (int i = 0; i &lt; hlnk.Count; i++)
		{
			// Remove if browser is not IE
			if (String.Compare(Request.Browser.Browser, &quot;IE&quot;, true, CultureInfo.InvariantCulture) != 0)
			{
				if (hlnk[i].Href.ToLower().Contains(&quot;ie.css&quot;))
					Page.Header.Controls.Remove(hlnk[i]);
				else if (hlnk[i].Href.ToLower().Contains(&quot;ie6.css&quot;))
					Page.Header.Controls.Remove(hlnk[i]);
			}
			else
			{
				// Remove if browser is newer than IE 6
				if (Request.Browser.MajorVersion &gt; 6)
				{
					if (hlnk[i].Href.ToLower().Contains(&quot;ie6.css&quot;))
					{
						Page.Header.Controls.Remove(hlnk[i]);
						break;
					}
				}
			}
		}
	}
 
	#endregion
 
	base.OnLoad(e);
}
</code></pre>
</div>

<div>
SeTech 
 
Could you repost the modified code please? Can't reproduce this exception on my machine. 
 
Are you just working on a plain Page or a control?
</div>

<div>
DaTribe- 
 
I'm afraid you're missing what I'm trying to do. I don't have a collection of CSS links on the page that I'm trying to filter. Basically, my ideal was that I have a folder called &quot;Styles&quot; in my project, where potential custom .css files will reside, and which one gets linked in to the Master Page will need to depend based on the value of Request.QueryString[&quot;page&quot;]. This isn't something based on browser versions or anything. 
 
Monkey- 
 
It's a Page...to be specific, I'm trying to post the code in Page_Load for my Master page. Yes, I'm sure it will make it easier to see the code yourself, so let me post it below. See what you think. You'll note intertwined with the code for the CSS there is similar code to choose the URL for an Image. As I noted in the initial Question post, the picture can also be customized based on the QueryString. The picture choosing code works perfectly. 

<pre><code class="code-10 nolinks" id="code-120684">protected void Page_Load(object sender, EventArgs e)
 {
 if (Request.QueryString.Count &gt; 0)
 {
 string logoUrl = &quot;Images/&quot; + Request.QueryString[&quot;page&quot;].ToString() + &quot;.png&quot;;
 FileInfo logoFile = new FileInfo(Server.MapPath(logoUrl));
 
 if (logoFile.Exists)
 {
 imgLogo.ImageUrl = logoUrl;
 }
 else
 {
 imgLogo.ImageUrl = &quot;Images/ThumbTack_Logo.gif&quot;;
 }
 
 string styleUrl = &quot;Styles/&quot; + Request.QueryString[&quot;page&quot;].ToString() + &quot;.css&quot;;
 FileInfo styleFile = new FileInfo(Server.MapPath(styleUrl));
 HtmlLink link = new HtmlLink();
 
 if (styleFile.Exists)
 {
 link.Href = styleUrl;
 }
 else
 {
 link.Href = &quot;Styles/default.css&quot;;
 }
 
 link.Attributes[&quot;rel&quot;] = &quot;stylesheet&quot;;
 link.Attributes[&quot;type&quot;] = &quot;text/css&quot;;
 Page.Controls.Add(link);
 
 }
 else
 {
 imgLogo.ImageUrl = &quot;Images/ThumbTack_Logo.gif&quot;;
 HtmlLink link = new HtmlLink();
 link.Href = &quot;Styles/default.css&quot;;
 link.Attributes[&quot;rel&quot;] = &quot;stylesheet&quot;;
 link.Attributes[&quot;type&quot;] = &quot;text/css&quot;;
 Page.Controls.Add(link);
 }
 }
</code></pre>
</div>

<div>
I think it's the fact that you're in a master page that's the issue... I'll get back to you on that.
</div>

<div>
I have done what you are trying to do in my master. I will get back to you also with the code necessary to achieve what you are looking for.
</div>

<div>
You may also want to add (string styleUrl = &quot;~/Styles/&quot; + Request.QueryString) instead of (string styleUrl = &quot;Styles/&quot; + Request.QueryString) If your Styles folder is in the Root of the website. 
 

</div>

<div>
Good deal, between the two of you, the page works like a charm. Good job! Thanks!!!
</div>

<div>
<div class="content wysiwyg-content">
On one of our sites, we're hoping to implement a feature that I'm not sure how to implement. It's ASP.Net 2.0, using C#. 
 
Inside the Master Page, there's an image not set to anything. Inside default.aspx, there's a GridView. Now, in the code-behind pages, the banner is set based on a QueryString variable called &quot;Page&quot; (if it exists, it tries to find an image file named the same thing as the Page querystring value. If it finds it, it sets it accordingly. If not, or if there is no QueryString value, it sets to a default image). In the default.aspx.cs Page_Load event, the QueryString variable Page is sent into a SQL stored procedure to get a DataSet to bind to the GridView. 
 
Now, what we would like to add is the capability for multiple CSS files, also named according to the Page QueryString value. So basically, on Page_Load for the Master Page, I'd like to be able to set the CSS file it uses (of course using a default if one doesn't exist, like the image). But I can't find anything like this on the Internet so far. Is there some property of Page for whatever CSS file it links to? I mean far more than just individual elements' CssClass properties, I'm looking for a way to basically dynamically set the &lt;link&gt; tag in the header based on what the QueryString contains.
</div>
</div>

On one of our sites, we're hoping to implement a feature that I'm not sure how to implement. It's ASP.Net 2.0, using C#.

Inside the Master Page, there's an image not set to anything. Inside default.aspx, there's a GridView. Now, in the code-behind pages, the banner is set based on a QueryString variable called "Page" (if it exists, it tries to find an image file named the same thing as the Page querystring value. If it finds it, it sets it accordingly. If not, or if there is no QueryString value, it sets to a default image). In the default.aspx.cs Page_Load event, the QueryString variable Page is sent into a SQL stored procedure to get a DataSet to bind to the GridView.

Now, what we would like to add is the capability for multiple CSS files, also named according to the Page QueryString value. So basically, on Page_Load for the Master Page, I'd like to be able to set the CSS file it uses (of course using a default if one doesn't exist, like the image). But I can't find anything like this on the Internet so far. Is there some property of Page for whatever CSS file it links to? I mean far more than just individual elements' CssClass properties, I'm looking for a way to basically dynamically set the <link> tag in the header based on what the QueryString contains.

Dynamically choose/change CSS at run-time

C# is an object-oriented programming language created in conjunction with Microsoft’s .NET framework. Compilation is usually done into the Microsoft Intermediate Language (MSIL), which is then JIT-compiled to native code (and cached) during execution in the Common Language Runtime (CLR).

Cascading Style Sheets (CSS) is a language used for describing the look and formatting of a document written in a markup language. Usually used to change web pages and user interfaces written in HTML, it can also be applied to any kind of XML document. CSS is designed primarily to distinguish the content of a document from its presentation.

The successor to Active Server Pages, ASP.NET websites utilize the .NET framework to produce dynamic, data and content-driven web applications and services. ASP.NET code can be written using any .NET supported language. As of 2009, ASP.NET can also apply the Model-View-Controller (MVC) pattern to web applications