<s>The `~` is the one you want, the ["application root operator"][1].  It can only be used in server controls, though.  Simply adding `runat="server"` might work:</s>

<s>`<link runat="server" type='text/css' rel='stylesheet' href='~/site1.css' />`</s>

Edit: Apparently the above does not work for `link` or `script` tags -- I don't know why.  But you could use `MapPath`, which is equivalent:

    <link type='text/css' rel='stylesheet' 
        href='<%= HttpContext.Current.Server.MapPath("~/site1.css") %>' />

<hr/>

Alternately, you could use a helper method, which has the advantage of allowing you to shift all references easily.  Something like:

    <link type='text/css' rel='stylesheet' href='<%= Application.GetCssPath("site1.css") %>' /> 

Where

    public namespace GlobalUtil
    {
        public class Application
        {
            public static string GetCssPath(string relPath)
            { 
                return System.Web.Configuration.ConfigurationManager.AppSettings["CssPath"] + relPath;
            }
        }
    }

For this you'd also want the `GlobalUtil` namespace registered in `web.config`; along with the `CssPath` setting for no-recompile changes:

    <appSettings>
      <add key="CssPath" value="/ParentLevel/" />
    <appSettings>

    <system.web>
      <pages>
        <namespaces>
          <add namespace="GlobalUtil"/>
        </namespaces>
      </pages>
    </system.web>

  [1]: http://msdn.microsoft.com/en-us/library/ms178116%28v=vs.100%29.aspx

This might be a beginner IIS question, but my application is having trouble loading a css file.

I made a test page named iisstart2.htm with three links to see where it would go to get references



    <link type='text/css' rel='stylesheet' href='~/site1.css' />
    <link type='text/css' rel='stylesheet' href='/site2.css' />
    <link type='text/css' rel='stylesheet' href='site3.css' />


I made two copies and put them here: 

* `C:\inetpub\wwwroot`
* `C:\inetpub\wwwroot\ParentLevel`

In the Edit Site settings, I have the physical path set to `C:\inetpub\wwwroot\ParentLevel`

When I browse to the first one (`http://localhost/iisstart2.htm`), here’s where it looks for css files: 

![enter image description here][1]

When I browse to the nested one (`http://localhost/ParentLevel/iisstart2.htm`), it looks here

![enter image description here][2]

When a link starts with `/`, then it's going all the way back to the root, but what I would have imagined it should have done is look for site2.css at `http://localhost/ParentLevel/site2.css`

**Question**

*Where can I go to change the default root directory?*

  [1]: http://i.stack.imgur.com/KEwNx.png
  [2]: http://i.stack.imgur.com/jb2iZ.png