XF 2.1 Hover background for user account navigation

[Mr Lucky]

The hover background for the user navigation on the right (account, inbox, alerts search) seems to be a transparent dark background. This is fine until I change the navigation bar itself to a dark colour (e.g. black). I then don't get background when for tap for mobiles.

Can someone please tell me how to style that hover background, I've looked unsuccessfully in Style properties. I can changed navigation row hovered tab, that only seems to apply to the main navigation on the left.

I can change add this to extra.less

    .p-navgroup    a:hover
    {background:@xf-borderColorHighlight;
    color:@xf-textColorAccentContent}

But it only affects the desktop style, however I define the media width.

Can anyone please help?

Thanks