all of which help IE9 and older to correctly render things like HTML5 and CSS3 elements that modern browsers support.
I’ve got a Windows 7 machine open and am testing in IE9. I’ve also used the IE inspector to shift over to browser mode IE8 and the menu continues to function so at the moment, I can’t replicate. I’ll send a screenshot shortly.
Please, try removing the entire contents of your Custom CSS, just temporarily and re-test. Does that change the result on your side?