Since style tags are not valid XHTML, TinyMCE disabled the ability to add them outside of the tags.
You have to add style tags to the valid children configuration
valid_children : "+body[style]"
Edit: This solution applies to version 3.4.2
Source
Since style tags are not valid XHTML, TinyMCE disabled the ability to add them outside of the tags.
You have to add style tags to the valid children configuration
valid_children : "+body[style]"
Edit: This solution applies to version 3.4.2
Source