Custom Css For One Particular Page

I want to style certain pages separate from the the rest of the website and the main CSS rules. How do I do this? Thanks

Basically on this page, I want to turn all the orange into blue. :)

You can create separate layout page for this page and and HTML block with < style > tag

I have tried a few different code variations, nothing appears to have any affect.

I've tried

.top-menu-mobiles {background-color: #15a4de;}
top-menu-mobiles {background-color: #15a4de;}
I just get a syntax error appearing where the block is.
top-menu-grid {background: #15a4de;}

You use incorrect class names. For example, try

.ty-menu__items {
    background: green !important;

Thanks! Managed to sort the whole page now. Cheers again.

You are welcome! :)