node sass does not yet support your current environment windows 64-bit with unsupported runtime (7) code example
Example 1: Error: Node Sass does not yet support your current environment: OS X 64-bit with Unsupported runtime (88)
npm update node-sass
Example 2: Error: Node Sass does not yet support your current environment: Linux 64-bit with Unsupported runtime (83)
npm install --save-dev node-sass