Add CSS to Application page in SharePoint 2010

Just a small thing to remember..

Css's can be registered in the PlaceHolderAdditionalPageHead section of an application page.
Like this:

<asp:Content ContentPlaceholderID="PlaceHolderAdditionalPageHead" runat="server"> 
<link id="Link1" href="<% $SPUrl:~SiteCollection/Style Library/mystyle.css%>" 

runat="server" type="text/css" rel="stylesheet" /> 
<SharePoint:ScriptLink id="jQueryCore" language="javascript" name="ui.core.js" 

runat="server"/> 
</asp:Content>