Examine source code of simple grey & orange

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "simple dark mode",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-030-0f935cfde055600d01a959c5c15353de.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(37, 37, 37)",
      "toolbar_text": "rgb(215, 226, 239)",
      "frame": "rgb(22, 22, 22)",
      "tab_background_text": "rgb(215, 226, 239)",
      "toolbar_field": "rgb(22, 22, 22)",
      "toolbar_field_text": "rgb(215, 226, 239)",
      "tab_line": "rgb(255, 107, 0)",
      "popup": "rgb(22, 22, 22)",
      "popup_text": "rgb(215, 226, 239)",
      "button_background_active": "rgb(255, 107, 0)",
      "icons_attention": "rgb(255, 107, 0)",
      "ntp_background": "rgb(22, 22, 22)",
      "ntp_text": "rgb(215, 226, 239)",
      "sidebar_border": "rgb(255, 107, 0)",
      "tab_loading": "rgb(255, 107, 0)"
    }
  }
}