[styles] Normalize Vendor Import Paths

[greaterweb]

Within the shared stylesheet assets, vendor imports would benefit from being normalized:

• prismjs - sans node_modules
• sweetalert - ../../node_modules
• gridle - node_modules

The only reason I encountered issues was due to the fact I was trying to customize/extend the stylesheets and import them into my local project. It required a bit of configuration to the node-sass includePath to get it working correctly.

Should be a relatively easy fix, as with my other ticket I'll try to submit a PR if time permits this week.