When there are style changes, they are underlined and they have a background color. The background color could be removed, otherwise the diff screen will look like a rainbow. The underlining is enough since style changes can be considered as minor.
Besides, this should be added to the explanatory caption. Here is a proposal to add it and try to make the text shorter.
Parts added to the right document.
Parts removed from the left document.
Click on the changed parts to go to the next or previous difference or use the left and right arrow keys to walk through the modifications.
With the 3 first lines showing the respective styles (See my ugly screenshot).