jquery mobile - Loader widget displays ajax-loader.gif with non-transarent background -

the loader in application looks above unwanted background surrounding it. cannot rid of background, same situation when use different transparent ajax-loading.gif. in same browser loader looks fine in demo application:

i using theme roller theme did not find setting there seems influence loader plus css loader looks identical in app , demo app.

any clues cause looks of loader?

i able work around setting theme not using:

$.mobile.loader.prototype.options.theme = "f"; 

my theme seems have messed looks of loader maybe because not using rounded corners, adding 1em corners (as in default theme) not rid of glitch.