Ubuntu Node Sass does not yet support your current environment: Linux 64-bit with Unsupported runtime 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: Windows 64-bit with Unsupported runtime
npm rebuild node-sass