Ion-app height for ads banner campaign

Hi

Is there a way to target the element <ion-app> programmatically to add an attribute.
I need to change the height to let ads banner appear at the bottom of the app when navigating on pages.

At the beginning i added an attribute on <ion-content> but’s it’s not the good way to do it, because we can see the previous page under the new page before the ads displays.
Another problem is that toast bottom appear behind that ads, and moving it with a css class isn’t a good solution.

So back to the main question, how can i add an attribute to <ion-app>

Anybody have an idea?