Here is the reply from developper team and it fixed.
"when you click on the "customize page" link to edit content with the page editor, you should see a "Style" Link right to the Edit tab. It leads to the view where you can create/edit a custom content stylesheet.
When in editing mode, you can choose a category, e.g. Text (Block) and then click the "Add Style Class" Button. You can then add your own custom css (e.g. writing-mode: vertical-rl) at the bottom of the form, save and come back to the page you want to edit."
more infomation, please lefer to following URL;
http://www.ilias.de/mantis/view.php?id=16833