I see some really beautiful HTML5/CSS3 sites out there and can't imagine someone doing it entirely with a text editor. I just assume the standard approach is to use something like Dreamweaver then drop down to code level for the fine tuning.
Most, if not all, professional developers will in fact code it entirely in a text editor like Sublime Text, or use an IDE like WebStorm. To be honest, if any of the companies I worked at was screening a Web Developer that said they used a WSYWIG, it would be interview over. Using a WSYWIG is not a good idea and will end up with markup that is not as maintainable, clean or semantic than someone who dives straight into the code. Designers are typically the types that will lean on WYSWIG's to avoid having to do any coding or to throw together quick protoypes. Anything that need to be production ready, is pretty much hand coded.
There are a lot of frameworks out there that people will use as a foundation. Check out HTML5 Boilerplate, Modernizr, CSS Normalize, Skeleton, and as Mixtilplix mentioned, Boostrap (which was originally developed at Twitter, but is now open source). Best advice I could give you, regardless of platform, IDE or editor choice, would be to avoid WSYWIG's and learn to hand craft your content. The future dividends of your work will be infinitely better.
If you come from more of a pure programming background, there is a trap many fall into. HTML and CSS is deceptively simple on the surface, but building beautiful sites that can scale, or be responsive and performant while being sematic is an art.
If you are really interested in Front End Development, I'd highly recommend any of the following books:
Designing with Web Standards (3rd Edition): Jeffrey Zeldman, Ethan Marcotte- If you build for the web, you pretty much have to read this. Zeldman started the standards revolution and has helped shape the web of today.
A Book Apart, HTML5 For Web Designers
A Book Apart, CSS3 for Web Designers
A Book Apart, Responsive Web Design
JavaScript: The Good Parts: Douglas Crockford- An absolute MUST read for anyone doing Javascript. Crockford is the Godfather of JS.
DOM Scripting: Web Design with JavaScript and the Document Object Model: Jeremy Keith, Jeffrey Sambells- A more elegant way to bringing interactivity to the web.
High Performance Web Sites: Essential Knowledge for Front-End Engineers: Steve Souders- Another extremely important book that will shape how you structure your code
Read these blogs:
A List Apart: For People Who Make Websites
AddyOsmani.com | Articles for developers
Lea Verou | Life at the bleeding edge (of web standards)
Paul Irish
Lastly, read this:
How Browsers Work: Behind the scenes of modern web browsers - HTML5 Rocks- Don't let the title fool you, thats some serious shit right there that everyone who makes content for the web should know.