How to access style sheets in index.js?

[CarolynnRen]

I tried document.getElementById("the id set for stylesheet in my widgets.gui") and document.styleSheets to gain some access to the style sheets, but none of them worked.

[SunsetRunner]

What do you try to achieve? Do you mean accessing element's class or id?

[CarolynnRen]

Thanks for replying. Actually I was trying to add an alternate stylesheet to my app and switch to it sometime as a notification display. I couldn't figure out how to do that, as a workaround, I just selectively hid some UI elements and made the notification messages and buttons visible. 

Is there a way to achieve some similar effect as the Fitbit standard notification?