Select layout for this specific Post only box is not responsive on tablets

At tablet breakpoints the options in “Select layout for this specific Post only” continue to display horizontally and flow into the right column instead of stacking. This occurs on tablets (I used an iPad2) in landscape mode (more than 850px and less than 1300px wide). This was first observed in Clean Retina 1.3.5 on WordPress 3.9.0 but is present in Clean Retina 1.3.8 and WordPress 4.1.1.