Change button height in WebDynpro ABAP

For a touchscreen I need to increase the height of my buttons in a ABAP WebDynpro Application. Because there's no attribute for the height I read that it should be possible to add an image to the MIME Repository and then add this image to the button. I also read that it might be possible to create a own theme with a .css file.

The last one sounds a little bit better to me. Does anyone know how I can create such a theme and apply it to my application?

Thanks for your help!

The simpliest way of resizing height is using MIME image, which I want to describe here:

1. Create your image with exactly those height that you need. The image could be opaque, transparent or whatever. Image format doesn't matter, as most common formats (jpg, gif, png) are supported.
2. Import it to your Webdyn Pro component like this: right click on component in repository tree, then
   -> Create -> MIME object -> Import
3. After image was successfully imported, just select it using imageSource property of button element, where you can find it on Component images tab.

Voilá! The button adopted the dimensions of the image.