I'm using polymer - so i guess that applies too. What I personally do is have views that use global styling from bootstrap/material depending on the project, an

I'm using polymer - so i guess that applies too. What I personally do is have views that use global styling from bootstrap/material depending on the project, and individual views are built from components that have their own styling, that can be overriden by app-wide one whenever needed. So far i never had problems with wrong styling caused by top level stylesheet.