Bootstrap with dhtmlxSuite 5.1

I use dhtmlxSuite 5.1 pro.

I have a problem, If we import bootstrap 3.3.7, then height of menu will change.

Please remove/add the import bootstrap css in html, you can see the change.

Remove bootstrap, the html is

Add bootstrap, the html is

if I want to let bootstrap css don’t change layout, should i do?