Tools for understanding HTML layout

Are there any tools other than Firebug that can help me figure out why my HTML is layed开发者_运维知识库 out the way it is? If you list any tools, please add what they can do which Firebug can't.

• WebKit's Web Inspector, used by Safari and Chrome.
• Opera's Dragonfly

Both do pretty much the same things Firebug does.
I'm usually using both Firebug and Web Inspector. Though I like Firebug more, I had a few errors that I wasn't able to trace using it (they were just listed as errors), but they showed up in Web Inspector.

It doesn't get much mention or much love, but I find Expression Web SuperPreview helpful when trying to debug layout issues.

I only use Firebug for JS debugging, I use Web Developer for Firefox for anything CSS or HTML related.

https://addons.mozilla.org/en-US/firefox/addon/60/

1. Great for CSS debugging - while Firebug will show you the CSS, Web Dev does it better giving you a nice window with line numbers so you can easily find what needs fixing, plus you can copy and paste from the window.
2. Shows underlying form information without looking at the source
3. Outlines various types of elements on the page
4. Resize the browser window to the common screen resolutions, or to a specified size (love this feature)

I wouldn't say that Web Developer is better than Firebug, just different.