Hidden Website Header Glitching Back In

Alright this may seem a little convoluted but bear with me.

https://mckaylakrygier.com/

I seem to be having trouble with my hidden header briefly re appearing whenever I click from page to page on my website. I wanted to use my header on a non linked page only and not on the rest of my site, so I embedded a code that would hide the header on each page I didn't want it showing up, and instead built a similar "false" header out of a new section, The problem is when I click the links to my other pages in this new header, it will take me to the page I want but in turn the hidden header will glitch into view for a moment. Is there any way to fix this? or is it something I'm going to have to deal with? It doesn't happen all the time but I'd rather it didn't do it at all.

Here is the code I embedded on the pages in case anyone was wondering:

<style>
  header#header {
    display: none;
}
</style>

Code add to Page Header Code Injection, will be always have this problem, you need to add to CSS instead, but if adding to CSS, you need to target with Page ID

Can you share link to page where you want to hide Header? We can give exact code with Page ID