war/src/main/webapp/css/style.css has various CSS errors as reported by HtmlUnit, such as
filter: alpha(opacity=40); /* msie */ -ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=50)";
These clutter log output when running HudsonTestCase/JenkinsRule tests, and might confuse standards-compliant browsers. Perhaps better to split browser-specific hacks into separate CSS files inserted only when the client identifies itself as that browser.
Forcing usage of a dinosaur like IE8, would need apologies indeed, even on the now officially dead Windows XP.