Allow CSS styling in node filtered HTML view?
I recommend using the WYSIWYG Filter module.
In the "HTML elements and attributes" textarea there is a list of allowed HTML tags. 'ol' should be present. If it is, add '[class|style]' to it which will make it look like this:

ol[class|style]

Or, you can add @[class|style] to the list to enable the style and class attributes on all allowed html tags.