Kathamo is a Minimalist CSS Framework for Rapid & Mobile-Friendly Development. Kathamo has a few easy ways to quickly get started, each one appealing to a different skill level and use case.
In Mac Safari, If I reduce the width of the window in the demo.html, I got a small rectangle at the bottom when you click on the menu icon (3 horizontal lines).
In Safari and Chrome, it appears immediately after clicking the icon.
In Firefox, you must enlarge then reduce the window after clicking the icon.