Hmmm. Well, dw does it's own insertion of crap code extras, depending on how you set it up.
I've been writing html/css for years (first website in 1995 approx.) I wouldn't give dw houseroom - for a variety of reasons.
First one is cost. It does NOTHING special for the money you pay.
Second one is the whole proprietary crap thing over again: how many people have railed at the fate that started them on the (older now) round of "I own a compaq, a gateway, etc. and I can only buy their version of whatever and it costs THREE TIMES what joeblow's version does" (and macs are still somewhat in that phase).... Well with dw, it's "teaching" people to use stuff like .lib setups and "layers" and so on.
Get a decent plain-vanilla editor like notepad++ or notepad2. Or if you MUST have some sort of visual (and I do myself use this.... though without bothering with the visual**), pay a LOT less and get TopStyle Pro from http://bradsoft.com/.
** I have two side by side editor panes, and a very small display set up below both of them. The only thing I use it for is color comparison in the css file - which is open in the right pane while the html files are open in the left pane.... I "see" what I'm doing using XAMPP as local server, with the site under dev open in a browser window - all the browsers: FF, IE, Op and so on....