Symptoms

Any browser within which K2 forms are being used renders the form without the main browser scrollbar. To specify, the main browser scrollbar is there when accessing a list, but opening a New, Display, or Edit Appit form makes the main browser scrollbar disappear. This is an error as the browser's default functions are being disabled by K2 forms.

This error happens with all major browsers. This error is noted by many users as they can only use the bottom of their screen in Appit forms.
 

Diagnoses

SharePoint-embedded Appit forms cut off at the bottom of the page with no outer scroll bar.

 

Resolution

This is by design, as by default, our iframe (DOM element with ID = "iframeMain") scales to 100% of the browser window's width and height with an internal scroll bar on the right that looks like an outer scroll bar but prevents the bordering SharePoint elements from moving.

Your custom site theme is horizontally shrinking the div container that contains our iframe, so the scroll bar moves along with it. We only supply the iframe to SharePoint, so we have no control over what happens outside of it.

What I would recommend is to make changes to the CSS in your theme such that the "iframeMain" element gets stretched vertically to it's max internal height, thus getting rid of the internal scroll bar and forcing elements to go below the visible window which would force an outer scroll bar on the far right. Note that this would cause SharePoint's bordering elements to scroll with the page as well.