Theme colour overrides

The #db0100 colour is hard-coded in several places in the SCSS, making it quite difficult for theme developers to override.

Doing something like:

:root {
  --simplesamlphp-color: #db0100;
}

and then referencing it elsewhere as e.g.:

.pure-button-red {
  background-color: var(--simplesamlphp-color);
  color: #fff;
}

would make it much easier to override the colour consistently by simply declaring an additional <style> element in _head.twig with the new --simplesamlphp-color variable definition. The same could be done with the other colours that are used.

I'd do this as a pull request, but I think this repo has complexity I do not understand :-)

Search the SCSS assets for the hard-coded #db0100 value and inspect _head.twig, which is the proposed place for theme overrides. Replace the repeated colour usage with consistently overridable variables, including the other colours where appropriate. Done means a style declaration in _head.twig can change the theme colour throughout the affected assets.