Amaya 11.3 leaves the border from the fieldset element inside the legend box instead of placing the legend box over the top of the fieldset box. Although for the test the background property could be dropped, there are real life situations where it is required. Suppose that div and legend backgrounds are set in a general stylesheet. But for a special form you want the legend background to match the div one. And you do not want to hardcode it because the general stylesheet may change. This is the spot where :transparent really makes sense! Check the look against any mainstream browser.