I am looking for development software that has a live preview of the page as you code it, and is aware of HTML5 and CSS3 syntax. Obviously it'd be useful if the live preview enngine was HTML5 and CSS3 capable too. I favor lightweight editors over heavyweight IDE's as I don't want much more than syntax highlighting, suggesting and checking, with the preview.
I have been using Topstyle 4, and whilst it seems to tick most of the boxes for me I find it lacking and a tad buggy, but can't seem to find any other software that fits.