Fix position/size of multi-locale language menu selector

The selector is behaving weirdly in two different ways:

1. It initially exceeds the height of the window (although the bottom portion is blank), but seems to fix itself when the user engages with it: language-long-menu
2. The "top" position seems to be completely dislocated from the menu-button, and is attached to the top of the viewport instead: language-top-menu