The max-width value may need to be increased a bit. The max-width value decides when the reduced padding gest applied.
On IE, 860px was soon enough, in your video it is still a bit too late, so just increase that value a bit until it works on all browser you care for
@media only screen and (min-width:768px) and (max-width:880px) {
.wvrx-menu a {padding-left:0.4em;padding-right:0.4em;}
}