Can’t Change Header Z-Index

Hello,
I’m using Astra (free) with Elementor (pro).

When scrolling down, some of the Elementor content covers the theme’s header (e.g. The “shape divider”, the testimonials carousel, the text of an animated title…)

I noticed that the header’s Z-Index is 1, so I tried to increase it, but it gets overridden somehow. I also tried to change the html code using Chrome’s Inspector, but it immediately gets changed back.

Is there a convenient method to change the header’s z-index?

Thank you!

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