There are several faces speedbar generates to provide a consistent color scheme across display types. You can customize these faces using your favorite method. They are:
Face used on expand/contract buttons.
Face used on Files. Should also be used on non-directory like nodes.
Face used for directories, or nodes which consist of groups of other nodes.
Face used for tags in a file, or for leaf items.
Face used to highlight the selected item. This would be the current file being edited.
Face used when the mouse passes over a button.
You can also customize speedbar’s initial frame parameters by changing
speedbar-frame-parameters. This variable is used to
set up initial details. Height is also automatically added when
speedbar is created, though you can override it.