A Beginner's Guide to Sass with Shopify — Part 3: Sass interpolation, Workflow and Object Oriented CSS - https://www.shopify.com/partners/blog/a-beginners-guide-to-sass-with-shopify-part-3

a-beginners-guide-to-sass-part-3-interpolation.liquid.scss

//  Escaping Liquid in SCSS.
//
//  Expected output:
//  a{
//    color: {{ settings.link-color }};
//  }

a{
  color: #{'{{ settings.link-color }}'};
}


//  Reuasble liquid:
$myVar: #{'{{ settings.font-family }}'};

h1{
  font-family: $myVar;
}

//  Using a sass variable from the current file:
$var1: #fff;
$var2: #{'{% if settings.colour %}{{ settings.colour }}{% else %}'}$var1#{'{% endif %}'};


//  Liquid if statement:
body{
 /* {% if settings.background-image %} */
  background: url(#{'{{ settings.background-image | asset_url }}'}) center no-repeat;
 /* {% else %} */
  background: whitesmoke;
 /* {% endif %} */
}


//  Liquid outside a css statement:
//  If we wrote /* {{ settings.custom-css }} */ then our compiled liquid would be inside the comments making it useless.
//  We need liquid to create the ending and opening comments when its compiled,
//  however if we wrote /* {{ settings.custom-css | prepend: '*/' | append: '/*' }} */ the string: ' | append: '
//  is still seen as being outside the comments.
//  We need to escape them untill liquid can create them so we add an extra character and then remove it.

/* {{ settings.custom-css | prepend: '*\/' | append: '\/*' | remove: '\' }} */

/* {% if settings.custom-css %}{{ settings.custom-css | prepend: '*\/' | append: '\/*' | remove: '\' }}{% endif %} */