Themes with image buttons - in sidebar only a small part of the button is shown

[torinfo]

@FayCross We've got loads of custom thmes and we're working through the changes. However, we still have an issue with thems using images. The Home button shows only a part of the image when the sidebar is enabled.

The same issue exists in flat blue. Do you have a solution for flat blue?

[FayCross]

@torinfo let me know if this fixes it. Thanks