http://yysource.com/2011/03/debugging-with-css-outline-all-elements/

* { outline: 2px dotted red }
* * { outline: 2px dotted green }
* * * { outline: 2px dotted orange }
* * * * { outline: 2px dotted blue }
* * * * * { outline: 1px solid red }
* * * * * * { outline: 1px solid green }
* * * * * * * { outline: 1px solid orange }
* * * * * * * * { outline: 1px solid blue }


http://www.marcofolio.net/css/css_trick_debug_your_html_and_css.html

* *:hover { border:2px solid #89A81E }                   /* Solid Green */
* * *:hover { border:2px solid #F34607 }                 /* Solid Orange */
* * * *:hover { border:2px solid #5984C3 }               /* Solid Blue */
* * * * *:hover { border:2px solid #CD1821 }             /* Solid Red */
* * * * * *:hover { border:2px dotted #89A81E }          /* Dotted Green */
* * * * * * *:hover { border:2px dotted #F34607 }        /* Dotted Orange */
* * * * * * * *:hover { border:2px dotted #5984C3 }      /* Dotted Blue */
* * * * * * * * *:hover { border:2px dotted #CD1821 }    /* Dotted Red */

http://bigemployee.com/4-simple-techniques-to-quickly-debug-and-fix-your-css-code-in-almost-any-browser/