“Additional CCS” Problem

I was customizing my SKETCH site and happened to notice an error message under the tab “Additional CCS.” Don’t know how long it’s been there, what it means, or how to resolve. It says:

There is 1 error which must be fixed before you can save.
Update anyway, even though it might break your site?

.sitelogo {
max-height: 600px px:;
}

.site-branding {
margin-bottom: 0;
}

.has-site-logo .site {
padding-top: 50px;
}

The page I need help with: [log in to see the link]