http-server is a simple binary to provide a static http server from a given folder.
HTTPSERVER_FILE_SERVER_COLOR_SET can be modified to use any of the colors listed on here.
Whenever you select a color combination, you will get a link at the bottom of the page. The link will include the color towards the end of the link:
<link rel="stylesheet" href="https://code.getmdl.io/1.3.0/material.indigo-pink.min.css" />
What you care about is the bit that says
indigo-pink. That's the color you will set in variable and run the following command to apply any changes:
ds -c up httpserver