TopStyle has many nice features to make a developer's life easier. For example, there is a color picker which produces the hex code for a given color. That's pretty much boilerplate, but it also includes a palette of harmonious colors to let you easily create an effective, balanced, color scheme for your design. As you select elements in the editor (for example, H1), all the possible properties are displayed in a list to the right (the list can be moved, of course), and edits made in that list are quickly reflected in the main editor. The reverse is also true--edit the text, and the property list updates.
TopStyle is a focused program, but a well done one. Anyone who edits or creates Cascading Style Sheets would do well to download the full-featured trial to determine if this program should be part of their toolbox.