The topbar is 100% by default, no need to set it again
Use the menu name for the menu toggle buttons

The secondary menu might not always be the secondary menu so this
changes it to use the menu name set by the user suffixed by “Menu”.

Credits to @turtlepod for the code and Renata from Theme Hybrid for the
report.

Closes #9
Use the button element instead of <h3> for the menu toggle buttons