When using HTLM5-Tags like <section> or <header> and assigning them a certain width via CSS, the preview window simply shows the contents one after another in one line and width reduced to the content. In the example below (CSS included for simplicity) only the "div"-tag works as expected.
If I open the document in a browser (Firefox & IE9) everything is fine. So this seems like a bug in DW to me - any chance it gets fixed? Or is there some option I've missed? I've already checked for updates (none) and the HTML5-Pack is installed. Happens in "Liveview"-Mode as well.