Similar to the issue
MSKINS-16 that was fixed for the Fluido skin the Default Skin ignores the width and height and border settings in the site descriptor.
The changes in site.xml were introduced here:
Created new issue
DOXIASITETOOLS-173 for the CSS issue described below:
The CSS in maven-base.css would anyways not allow for a border around any image - one would need to create a new skin for borders or remove the border:none from the img tag.