Of course, I was embarrassed at neither remembering this nor coming up with a solution before having it pointed out. Nonetheless, I remembered when first getting acquainted with Fitnesse a mention of customization of the stylesheets in the user guide.
Digging around a bit, I discovered a very simple solution. I created two png files, pass.png and fail.png and placed them in c:\fitnesse\files\images. Then I modified c:\fitnesse\files\css\fitnesse.css as follows:
@import url( "/files/css/fitnesse_base.css" ); .pass { background-color: #AAFFAA; padding: 0px 0px 0px 20px; background-image: url("../images/pass.png"); background-repeat: no-repeat; } .fail { background-color: #FFAAAA; padding: 0px 0px 0px 20px; background-image: url("../images/fail.png"); background-repeat: no-repeat; zoom: 1; } #test-summary { padding: 0px 0px 0px 20px; }