Examine source code of Heart-On

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Heart-On",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-005-f5f3cf677b1f132c75ddc7bd319dd1fc.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(89, 0, 76)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(112, 112, 112)",
      "tab_background_text": "rgb(29, 0, 47)",
      "toolbar_field": "rgb(0, 0, 0)",
      "toolbar_field_text": "rgb(0, 209, 249)",
      "tab_line": "rgb(0, 255, 159)",
      "popup": "rgb(255, 255, 255)",
      "popup_text": "rgb(179, 0, 126)",
      "ntp_background": "rgb(101, 14, 121)",
      "sidebar_border": "rgb(92, 74, 180)",
      "tab_loading": "rgb(0, 255, 159)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{bc3ed0c8-acc5-4c2b-b6e4-05ebf45046e7}"
    }
  }
}