As a Demo
You can copy and paste this section of code and paste it in and see what it does.
You'll just see the result where the inline styles are replaced by the classes I have defined that my Text Editor Kate produces.
Instructions: For PC users (Macs will be different)
Click your Mouse in the Text Area Below and press Ctrl-A (to select all), Ctrl-C (to copy) and then click in the form above and press Ctrl-A (if there is already text there) and Ctrl-V to paste. Then click the Convert Button and Hey Presto!