Remove data-iconshadow="false" from JQM Collapsible title - css

Question

I have been trying to do this for a while with CSS and also data attributes but it is driving me up the wall. It's easy to remove data-iconshadow from buttons, but from collapsibles, not so.
In the Developer Console I can see JQM is applying "data-iconshadow='true'" even after I told it not to using this code (in several places):
<div data-role="collapsible-set" data-iconshadow="false">
<div data-role="collapsible" data-theme="f" data-collapsed-icon="baby" class="ui-icon-nodisc" data-iconshadow="false" data-expanded-icon="arrow-u">
<h2 data-iconshadow="false">0-12 Months</h2>
**insert content here**
</div>
</div>
Yet it still generates this code:
<span class="ui-btn-inner"><span class="ui-btn-text">0-12 Months<span class="ui-collapsible-heading-status"> click to collapse contents</span></span><span class="ui-icon ui-icon-shadow ui-icon-arrow-u"> </span></span>
Yeah it is still writing the data-iconshadow to be true. And I'm not even sure how to target injected attributes with CSS so I am not having much luck with that either. If someone could shed some light on the subject, I would be most grateful.

Answer 1

Working example: http://jsfiddle.net/Gajotres/2NCjb/
HTML:
<div data-role="collapsible-set">
<div data-role="collapsible" data-theme="f" data-collapsed-icon="baby" class="ui-icon-nodisc" data-iconshadow="false" data-expanded-icon="arrow-u" id="custom-collapsible">
<h2 data-iconshadow="false">0-12 Months</h2>
**insert content here**
</div>
</div>
CSS:
#custom-collapsible h2 .ui-btn:after {
background: transparent !important;
}