I’m designing this login form using the GGS responsive grid (CSS) and although it looks cool on desktop browsers, it miserably breaks in mobile browsers (e.g. Android web browser, Mobile Safari, etc). How should I properly fix this inconsistency?

Above: layout breaks in Mobile Safari (left), but not in desktop browsers like Chrome (right).
I solved the issue by removing the
widthparameter from the buttons, as it somehow seems to be interpreted differently across both mobile and desktop browsers in mobile resolutions.