grass files are a form of css (style sheets), used during rendering of the web page (not part of a cypher query). Each javascript graph display library may have slightly different needs (and may not take a grass file exactly). Here is a list of viz options Graph Visualization Tools - Developer Guides I'm guessing you are using one of the common libraries (e.g. d3.js, cytoscape.js), and displaying the graph on a web page? In that case the nuanced details will vary a bit by library. It is best to check the docs for the one you choose to use. I've been using cytoscape.js because I was already using the desktop application Cytoscape...
cytoscape.js has an example Cytoscape.js tutorial demo showing a user selected active style sheet drop down select list. The Cytoscape application can export the style sheets for use with cytoscape.js, "most" of the styling configurations in Cytoscape (the application) works in cytoscape.js (the javascript developer library). See caveats on in their docs.
what is your stack? using flask or django? or?
