Stylizer helps you style websites in a fraction of the time.
Real-time CSS - Immediate feedback saves countless hours. Say goodbye to the reload button! In Stylizer, your changes are immediately displayed in all browsers, in real-time - literally as you type or move the mouse. This is a substantial productivity boost for designers of all skill levels.
Size faster with grips - Size Grips allow you to accurately resize any CSS dimension by clicking and dragging the mouse. Click, hold, and drag, and watch your page update in real-time and achieve perfection on your first try. Take the guess work out of sizing. Find the exact spot where that stubborn div wraps. Or use them to perfectly position a background image.
Two-click color changes - Tweak any color in your style sheet to find the perfect hue, saturation and luminance level for that exact look, in just two clicks: one click on the CSS declaration, another on the color picker which appears automatically. Stylizer provides two HSL-based color pickers and an opacity channel slider that generates RGB-based colors that work even on legacy browsers. Never guess another hex color code ever again!
Take control of repetitive tasks - The Remote Control makes many repetitive tasks a one-click operation. Most buttons here double as size grips, allowing you to save time with maneuvers like, for example, mousing down on the "background-position" button to insert a new declaration and starting to adjust it immediately by dragging the mouse. It's intelligent, too: when a declaration is already present, its button appears pressed, and Stylizer will adjust what you have instead of inserting. Or, right-click on a pressed button to delete a declaration without even looking for it.
Write error-free CSS - Stylizer knows all the latest CSS3 standards, and provides a real-time warnings list that updates without delay, as you type. You'll also see a subtle red underline wherever your CSS does not validate. Stylizer even recognizes many common CSS "hacks" to ensure that the warning list only contains actionable errors.
What's new in Stylizer
Note: Now requires OS X 10.9 or later.
Release notes were unavailable when this listing was updated.
For those who don't want/need wysiwyg, I think the free web extension Stylish could be an interesting alternative, especially for small tweaks, as it even work on existing websites. ;-) — haven't tried it on structure elements, but ok for colors and fonts.