When resizing the browser window to make it narrow, the part of the last tab following to the next line.
The problem is reproducible on all OS's with different browsers.

Effected tests below with jdk8 from http://wiki.se.oracle.com/display/JPG/JavaDocOptionalGrouping+Test+cases:
javadoc/OptionalGrouping/Class_A
javadoc/OptionalGrouping/Class_B
javadoc/OptionalGrouping/Class_C
javadoc/OptionalGrouping/Class_D