Improve Sass layer

[ffoodd]

A few conventions could help newcomers a bit:

• $_ for private variables,
• !default flag for public variables, to ease customization,
• use Dart Sass new module system,
• etc.

[kawaljen]

Hey, I am new to open source contributing, Can I work on this issue?

[ffoodd]

You may give it a try if you're comfortable enough with Sass best practices—however I don't have a clear goal on the topic, so not quite sure of what can be done.

[kawaljen]

Ok I'll leave it, cause the sass code seems pretty well as it is.. but maybe I have missed something

[ffoodd]

Thanks for your interest though!