Custom master page for dialogs

I am using a custom master page for branding, but the way I开发者_开发知识库 have designed it makes popup dialogs (like new item for lists) look terrible. I know I could probably change the design to make it work, but that would break the actual page (which for the moment looks perfect just the way it is).

My question therefore is this: Is it possible to change the masterpage only for dialogs and popups?

The standard v4.master page looks just fine for dialogs when using my custom theme so branding is not such a big deal here.

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I ended up messing with the design instead. This gave a satisfactory result.