Examine source code of Steamapp Theme

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Steam Theme",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-009-f069b97f439938a011297c84464f0df6.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(36, 40, 47)",
      "toolbar_text": "rgb(231, 236, 244)",
      "frame": "rgb(23, 29, 37)",
      "tab_background_text": "rgb(163, 170, 185)",
      "toolbar_field": "rgb(0, 0, 0)",
      "toolbar_field_text": "rgb(163, 170, 185)",
      "tab_line": "rgb(26, 156, 250)",
      "popup": "rgb(61, 68, 80)",
      "popup_text": "rgb(231, 236, 244)",
      "tab_loading": "rgb(26, 156, 250)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{150bd51a-16e4-401c-aa80-3dd0eab36d38}"
    }
  }
}