Solis enables you to easily preview SCSS and LESS as you write it. In order for Solis to handle the realtime processing, your .scss and .less files must reside at the same level as the the .css file that the processed style sheet would replace.
In the example below, you can see the style.less and style.scss are located at the same level as the style.css.
Please note: Solis does not handle the actual processing of production ready CSS style sheets from the LESS and SCSS files. Solis only supports the processing of LESS and SCSS as part of the live previewing experience.