All Xenforo versions suffer from that. Typical XenForo prefix placement for CSS3 values: border-radius: 2px; -webkit-border-radius: 2px; -moz-border-radius: 2px; -khtml-border-radius: 2px; /* Who does even use that? */ But this should be: -webkit-border-radius: 2px; /* I wouldn't include even that */ border-radius: 2px; Or for box-shadow we have this: box-shadow: 1px 1px red; -webkit-box-shadow: 1px 1px red; -moz-box-shadow: 1px 1px red; -khtml-box-shadow: 1px 1px red; And again this should be: -webkit-box-shadow: 1px 1px red; /* For very very old webkits */ box-shadow: 1px 1px red; To sum up: unprefixed property always should go the last, there are a lot of articles about this and the main reason for that is compatibility issues. When we place prefixed property at the end, browser will always use the old-standard version of this property. But when we have the unprefixed one at the end, browser can ignore it if it's not compatible or understand it according to the modern syntax of that spec. (for example when linear-gradient spec. changed). So far all prefixed CSS3 properties in XenForo should be fixed. Thanks.