DokuWiki's presentation can be controlled completely by changing its stylesheets (CSS). The default template includes four stylesheets:
design.css | view | download | controls the look of dokuwiki's “chrome”, that's the titles, bars, buttons, etc. |
layout.css | view | download | controls the look of the wiki page itself |
print.css | view | download | controls what gets printed and how it looks |
rtl.css | view | download | makes layout corrections to support right to left languages |
These files can be found in [your.dokuwiki.root]/lib/tpl/[templatename]/
Although it is possible to modify the default template stylesheets, it makes more sense to make a copy of the whole template, change the dokuwiki template setting to the new template and modify the CSS files of the new template. This way, if there are any problems, you can always change the template setting back to default. For more information on how DokuWiki handles stylesheets and its CSS dispatcher refer to css. For information about templates, and a list of available templates refer to templates.
Simply copy over the problem stylesheet with an original, either from your most recent Dokuwiki download or from the most recent sources in the links above.