The Icon Menu' on tablet is too Small.

Hello to all Forum, I developed a mobile application with SC8.1.
I have a problem when the ‘application runs on the Tablet,
the menu button’ is too small i would enlarge the size of the 'icon menu,
I tried to change the ‘image of the menu button’ by inserting a bigger
in section CSS bUTTON, but does not solve the problem
Thank you for your response.