Help with Header glitching

Hi all,

I'm suddenly having an issue with my Header that I wasn't having before. Whilst I am using CSS code on my website, I don't believe I've done anything recently that is new to break my Header?

I've screen recorded what's going on as it's hard to describe which you can see here - 

Basically my header only returns to the style I want it once I've made any kind of adjustment, be it add a button, social link or opacity change. Upon saving it reverts back to the glitched version?

Is there any code to lock it or something I'm missing to fix it?
Any help would be greatly appreciated.

Hi

What is site url?