Change header color on a specific page!

Hello! I would like to change the header color on this page before I scroll as it is transparent and I cannot view text!

Here is the link: http://beta.ahadgroup.co.uk/about-us

Thanks in advance!

Hi there,

Because your logo contain a white text, I think it’s better if you are using transparent with blue color to the header.
Add this to the Customize > additional CSS

#masthead {
    background-color: rgba(49, 70, 137, .5);
}

Hope it help.

Regards,

Now all the pages have that colour! How do I just apply it to the about page?

Replace the code in above with this:

.page-id-198 #masthead {
    background-color: rgba(49, 70, 137, .5);
}