Not OTB, but it's really very simple to implement a very nice mechanism.
Simply add this to your portal_normal.vm:
[tt]<body class="$css_class ${locale.toString()}">[/tt]
Then anywhere in your theme's css you can pre-qualify
definitions you want applied, when a particular language is selected, with the locale
string.
e.g.
[tt].fr_CA .some_class {
...
}[/tt]
HTH!
