All browsers have built in developer tools that can assist you when building or troubleshooting web pages without the need to download the page into an HTML Editor or try & sort through the source code. The safari Develop menu is a bit more hidden than the other browsers, so you must go into the preferences area and turn it on. Here is the command where you can locate and turn on the ability to use this handy feature within Safari:
Settings Icon->Preferences->Advanced Tab->Show develop menu in menu bar
To access this menu bar once it has been turned on, go to the Display icon (looks like a page in the upper right before the options icon) and choose Develop from the list.