CSS editor

The proxy can be used to insert locale-specific CSS rules into the site being served. The rules are inserted as the last element of the head on every page served through the proxy. A very common use case for this feature is RTL conversion of a website: almost always necessary when one of the target languages is Arabic.

It is good practice to make each CSS rule language specific (the proxy will always insert the appropriate locale code into the HTML):

html[lang="de-DE"] ul.one-selector li a {
  float: left; 
}

html[lang="fr-FR"] .another-selector h2 {
  height: auto;
}

If you omit the html[lang="fr-FR"], the CSS rule will be applied in all target languages, which might not be the behavior you expect.