Support header branding

[jp7677]

Generate a stylesheet containing colors from custom properties from the
view configuration. This allows a more customized branding of the header
and the menu.

Fall back to the current grey if no custom branding is specified.

[jp7677]

I struggled slightly with the naming, feel free to suggest other names for styles, properties or the css file name.

[dirkgroot]

Very cool, thanks! I've added some feedback.

[jp7677]

All issues should be addressed. The remaining question is, do we also want to colorize links? For that we just need to add the following to the generated css.

        a {
            color: $primary!important;
        }
        li.is-active a {
            border-bottom-color: $primary!important;
        }
        li a:hover {
            border-bottom-color: $primary!important;
        }

[dirkgroot]

I think it's best to add customization of link colors in a separate PR. This is already a very nice improvement. When it comes to customizing link colors, we'll have to think about whether or not we want to use the primary/secondary colors or maybe a separate one.

I'm merging this PR.

[jp7677]

I think it's best to add customization of link colors in a separate PR. This is already a very nice improvement. When it comes to customizing link colors, we'll have to think about whether or not we want to use the primary/secondary colors or maybe a separate one.

yeah I had similar thoughts, that’s way I hesitated. Thanks!