Examine source code of Arc Theme (Adapted)

{
  "manifest_version": 2,

  "applications": {
    "gecko": {
      "id": "arc-theme-adapted@mochi",
      "strict_min_version": "67.0"
    }
  },

  "name": "Arc Theme (Adapted)",
  "version": "2019.10.23",
  "description": "Based on Arc Theme by Afnan Khan. Restored new tab page to original light theme and increased contrast on tab text.",

  "icons": {
    "48": "icon.svg",
    "96": "icon.svg"
  },

  "theme": {
    "colors": {
      "frame": "#E7E8EB",
      "frame_inactive": "#E7E8EB",

      "tab_text": "rgb(42, 53, 78)",
      "tab_background_text": "rgb(62, 73, 98)",
      "tab_background_separator": "#5C616C",

      "tab_line": "#5294E2",
      "tab_loading": "#5294E2",
      "icons_attention": "#5294E2",

      "toolbar": "#F5F6F7",
      "toolbar_top_separator": "#CFD6E6",
      "toolbar_bottom_separator": "#DCDFE3",
      "toolbar_vertical_separator": "#DCDFE3",

      "toolbar_field": "#FFFFFF",
      "toolbar_field_text": "#5C616C",
      "toolbar_field_border": "#CFD6E6",
      "toolbar_field_separator": "#CFD6E6",

      "toolbar_field_focus": "#FFFFFF", // Firefox 61
      "toolbar_field_border_focus": "#5294E2", // Firefox 61

      "toolbar_field_highlight": "#5294E2", // Firefox 67
      "toolbar_field_highlight_text": "rgba(255, 255, 255, 0.9)", // Firefox 61

      "button_background_hover": "rgba(0, 0, 0, 0.085)",
      "button_background_active": "#5FA1E6",

      "bookmark_text": "#5C616C",

      "popup": "#FFFFFF", // Firefox 60
      "popup_text": "#5C616C", // Firefox 60
      "popup_highlight": "#5294E2", // Firefox 60
      "popup_highlight_text": "rgba(255, 255, 255, 0.9)", // Firefox 60

      "sidebar": "#F5F6F7", // Firefox 63
      "sidebar_text": "#5C616C", // Firefox 63
      "sidebar_border": "#DCDFE3", // Firefox 64
      "sidebar_highlight": "#5294E2", // Firefox 63
      "sidebar_highlight_text": "rgba(255, 255, 255, 0.9)" // Firefox 63
    }
  }
}