Hi Dan!
I just checked the studysquad page on your website and it looks like you were able to get the Header and Footer hidden as expected. I also checked the page markup and found the custom CSS rules responsible for changing the display for those elements:
body.page-id-107 #masthead {
display: none;
}
body.page-id-107 #colophon {
display: none;
}
There are some default rules in our Crio WordPress theme that use the #masthead and #colophon IDs to set the display: flex style for those page elements and I believe they were responsible for overwriting your previous custom CSS since any rules that target IDs have high specificity than rules that only target element types.
Hopefully that page is displaying as expected for you now and please let us know if there is anything else that we can do to help!