Preview Page looks different to Edit Mode Page

I’ve been trying to fix an issue with my website and for a few days now but without success. The page I’m currently working on looks very different in preview mode. The header is completely misaligned, and the hamburger menu appears very big at the bottom even when looking at it on desktop (something might be wrong with the CSS file?). I have attached a few images, some in edit mode and some in preview mode.

I’ve googled extensively and feel like I’ve tried everything that was suggested (cleared cache, switched theme temporarily, disabled most plugins, regenerated CSS styles (Elementor > Tools > Regenerate CSS)). Nothing has worked so far. Has anyone encountered a similar issue and managed to fix it?

Here is some more information about the tools I’m using:

Theme: 
Elementor Child

Plugins: 
Akismet
Crowdsignal Forms
Elementor
Elementor Pro
Jetpack
Super Page Cache

And here are the images:

Edit Mode (like I want it to look)

Preview Mode

The page I need help with: [log in to see the link]