Examine source code of Drafting Vellum

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#edeaea",
      "tab_background_text": "#000000"
    }
  },
  "version": "2.0",
  "name": "Drafting Vellum",
  "manifest_version": 2,
  "description": "Light, textured theme based on the look of drafting vellum.  For those that want a neutral theme with high visibility for icons and text."
}