Examine source code of Subtly Dark

{
  "name": "Subtly Dark",
  "version": "1.0",
  "description": "A subtle, dark theme for your browser",
  "manifest_version": 2,
  "theme": {
    "images": {
      "theme_frame": "images/theme_frame.png",
      "theme_toolbar": "images/theme_toolbar.png",
      "theme_tab_background": "images/theme_tab_background.png",
      "theme_ntp_background": "images/theme_ntp_background.png"
    },
    "colors": {
      "frame": [
        39,
        39,
        39
      ],
      "toolbar": [
        43,
        43,
        43
      ],
      "tab_text": [
        255,
        255,
        255
      ],
      "tab_background_text": [
        255,
        255,
        255
      ],
      "bookmark_text": [
        255,
        255,
        255
      ],
      "ntp_background": [
        27,
        27,
        27
      ],
      "ntp_text": [
        255,
        255,
        255
      ],
      "ntp_link": [
        6,
        55,
        116
      ],
      "button_background": [
        0,
        0,
        0,
        0
      ]
    },
    "tints": {
      "buttons": [
        0,
        0,
        0.93
      ]
    },
    "properties": {
      "ntp_background_alignment": "bottom",
      "ntp_background_repeat": "no-repeat"
    }
  }
}