h5bp/html5-boilerplate — comment on commit aa0396eae757c9e03dda4e463fb0d4db5a5f82d7
File:  line 0
By necolas:

Turns out IE6 leaves a 1px faint trace of the text because `color:transparent` isn't supported by IE6/7/8 (but IE7/8 hide the text properly anyway). So if you to 100% remove any trace of text in IE6, you might have to throw an IE6 hack in there.