title of borderlayout north/south shouldn't rotate 90 degrees

Steps to Reproduce

<borderlayout >
    <north title="North" maxsize="300" size="50%" open="false" >
        north
    </north>
</borderlayout>

1. Use the atlantic theme

Current Result

The titles of .z-north-title and .z-south-title are rotated 90 degrees.

Expected Result

The titles of .z-north-title and .z-south-title are not rotated.

Debug Information

The other themes (namely, Breeze, Sapphire, Silvertail, and Default) are not affected in 9.6.2.