Menu button on mobile site – SKSDEV theme

Dear,

This is the demo site http://steven-voz.com/demo

I have got a problem with SKSDEV theme. When I open site on mobile, or resize the brower to smaller, the Menu Button not work.

Let you see 2 image here

On website SKSDEV.com, it is okie http://thapbiaonline.com/wp-content/uploads/2015/04/sksphpdev-01.png

On my site, no okie: http://thapbiaonline.com/wp-content/uploads/2015/04/sksphpdev-02.png