Artisteer "tries" to be responsive for ipad and iphone, how effective they are is questionable/debatable.
They do a lot of things with javascript in their strategy to make it responsive. If you don't like the responsive behavior, you can remove the javascript from the layout.master file, it looks like this:
<portal:SkinFolderScript ID="sfs2" runat="server" ScriptFileName="script.responsive.js" AddToCombinedScript="false" />
Just remove that and it may help but it will also disable some of the good responsive stuff, so you'll ahve to see which way is best for you.
You could also remove the slogan or use a separate mobile skin and leave the slogan out of it.