Hello,
The 404 error page background color is used from the “Blog” settings page. So, in order to change the background color on 404 page, you will have to change the same on blog page, too.
If it’s not that urgent, you can wait a short period while we announce an update which will include the background color change option just for 404 page.
Another workaround to change the header area grey background is to use the following CSS code:
section#page-title {
background: #000 !important;
}Robert
