I have changed the dimensions of my custom header image for the Ocean Mist template by changing them in the CSS. I have even changed the CSS to display the image I would like there and it looks fine.
However, I would like for my non-technical friend to be able to upload a new image using the Custom Image Header interface that is part of the WP Dashboard. When I go to upload an image there, it still constrains the dimensions to the ones that come with the Ocean Mist template as default.
How can I get WP-Admin to recognize and allow my new dimensions when I go to upload a new image through the Custom Image Header interface?