Remove header/footer - Maple template

I have 4 unlinked pages I want to remove the header and footer from - using them as landing pages. We use the Maple template. I have tried adding code to the page header code injection section in the advanced settings but it brings up text at the top of the page and doesn't remove anything.

Does anyone know what code works?

https://www.theshackrevolution.co.uk/brochure-venue-tour

Can you share link to a page? Wee can check easier.

@tuanphan https://www.theshackrevolution.co.uk/brochure-venue-tour

Add to Brochure venue tour Page Settings > Advanced > Header

<style>
  header.Header.Header--top {
    display: none;
}
  .Mobile-bar.Mobile-bar--top {
    display: none;
}
  .tweak-footer-show .Footer {
    display: none;
}
</style>

Thank you @tuanphan I have just tried this and unfortunately it didn't work. Do I need to change anything in the site's general settings at all?