Removing Line on a Single Page & Removing Footer

I am trying desperately to remove the title and line beneath it on ONLY ONE PAGE of my site. I can successfully delete the title and line on ALL of my pages using

.entry-header {
display: none !important;
}

And I have tried using this code to change only one page

.page-id-377.entry-header {
display: none !important;
}

as well as

#page-id-377.entry-header {
display: none !important;
}

And nothing has worked. Also, I’d love to get rid of the gray bar across the bottom that promotes wordpress. If someone could help me with this, it would be great! I am using the theme Harmonic. Here is my website link:
https://plausibledeniabilitydesigns.com/