How do I have a full bleed gallery sit behind my transparent header?

Hi, Im hoping someone can help me, I have a page on a portfolio I am making and the first section is a full bleed gallery slideshow. My header throughout the website is transparent and fixed so that only the logo and buttons remain in place as you scroll. Currently when this page loads up the gallery sits beneath the header which reveals the background colour of the gallery section.

How do I make it so that the gallery reaches to the top of the page and has the header logo and buttons sitting over the top of it?

It currently looks like this at the top of the page

I want it to look like this without having to scroll down as I have done here

Thanks a lot!

You try this code to Website > Website Tools > Custom CSS. If it doesn't work, you can share site url, we can check easier.

body.homepage article section:first-child {
	padding-top: 0px !important;
}
body.homepage header#header {
	background-color: transparent !important;
}