CSS - :-moz-system-metric(windows-default-theme)

HTML Content

<p id="defaultThemes">
  This paragraph should have a green background with Luna/Royale/Zune/Aero
  Windows themes and red with other themes.
</p>

<p id="nonDefaultThemes">
  This paragraph should have a green background with Windows Classic or
  third-party themes and red with other themes.
</p>

<p id="notSupported">Theme detection is not supported.</p>

CSS Content

#defaultThemes,
#nonDefaultThemes {
  background-color: #FFA0A0;
}

#defaultThemes:-moz-system-metric(windows-default-theme) {
  background-color: #A0FFA0;
}

#nonDefaultThemes:not(-moz-system-metric(windows-default-theme)) {
  background-color: #A0FFA0;
}

#notSupported:-moz-system-metric(windows-default-theme),
#notSupported:not(:-moz-system-metric(windows-default-theme)) {
  display: none;
}