It's now possible to add a [params.colors] section to config.toml to
configure the colors the site uses. It is used like this:
[params.colors]
background = "#81c6ff"
foreground = "#edf7ff"
hover = "#ffba82"
Breaking changes: The SCSS variables have been renamed.
* $background-1 is now $color-background
* $default-light is now $color-foreground
* $default-dark is now $color-hover
See #4
