To use this real time CSS editor all you need to do is to change any property of the text using the table property and click one of the three buttons on the top. Button Show this style will produce the code corresponding to the changes you've made in the table. You'll see this code in the text area above, but this new style will not be applied to this text. To apply this style use button Apply this style. This button will apply the style which is displayed in the text area. So if the text area is empty don't expect much. You can make any modification to the displayed style before applying it. Just manually type them in. Button Show and Apply combines the action of the described buttons. And finally, button Reset will reset the table values to their defaults and restores the original form of this text.
Enjoy!
PS If you point mouse cursor on the name of any property you'll get a pop-up hint about that property.
PPS Almost forgot. Here is a picture Resume: to see what CSS can do the following:

set all desired properties in the table on the left

click on the Show and Apply button

enjoy