Examine source code of the best browser.....

{
  "name": "the best browser........",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "firefox.jpg"
    },
    "colors": {
      "frame": "rgba(63, 161, 242, 1)",
      "tab_background_text": "rgba(252, 167, 8, 1)",
      "toolbar": "rgba(78, 0, 235, 1)",
      "bookmark_text": "rgba(255, 166, 0, 1)",
      "toolbar_field": "rgba(255, 204, 0, 1)",
      "toolbar_field_text": "rgba(255, 166, 0, 1)"
    }
  }
}