Examine source code of Grassy hills

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Sunny day",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(3, 255, 0)",
      "toolbar_text": "rgb(0, 0, 0)",
      "frame": "rgb(0, 170, 255)",
      "tab_background_text": "rgb(0, 0, 0)",
      "toolbar_field": "rgb(1, 127, 0)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgba(255, 255, 255, 0.32)",
      "popup": "rgb(142, 86, 30)",
      "popup_text": "rgb(255, 255, 255)",
      "frame_inactive": "rgba(0, 170, 255, 0.42)",
      "popup_border": "rgb(142, 86, 30)",
      "tab_selected": "rgb(255, 255, 0)",
      "tab_loading": "rgba(255, 255, 255, 0.32)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{c854710e-9be7-48bd-8b90-8e9b2c1a08d3}"
    }
  }
}