changing my jquery mobile theme changes my css styling

Question

I have a collapsible set that I create on my website which looks similar to this:

Answer 1

Applying a theme changes the look and feel of HTML elements as here

div.setAttribute("data-theme", "c");

data-theme might be having a CSS class of its own which is effecting your webpage design

Are you using any CSS framework like BootStrap? Try adding this theme element to the exact div where you wish a design change