Flux is the incredible Web Design App from The Escapers
Flux 6 is the latest release of the killer Web Design App for the Mac.
Flux 6 introduces support for Responsive design using Skeleton or Bootstrap, a totally revamped UI, and 100s of bug fixes and usability improvements.
A totally re-written Code Editor makes manual code adjustments easier than ever, and WYSIWYG changes to your pages are simpler too, with a clearer workflow.
Flux has an amazing WYSIWYG engine (What You See Is What You Get). In Flux, you don't need to code everything, or even anything, you can drag images onto your page, adjust sizes with the drag handles, even adjust CSS properties such as margins and padding. You can even adjust external CSS properties this way.
Of course, you want to code too, Flux has a rebuilt Code Editor that's better than ever before. Importantly, Flux has no distinction between generated and hand-crafted code, so you can still use the WYSIWYG stuff, even on code you've typed yourself.
Flux supports FTP and SFTP, which means you can work directly on the server copy of your site. Remember to keep a backup!