Firefox has a hidden feature for web designers: You can find line numbers on the View Source page.
To find line numbers:
- From the Firefox menu, select View > Page Source. Firefox opens the page source in a new window.
- Type Control L (Windows) or Command L (Mac). Enter a line number and click OK. Firefox takes you to that line number in the source code.
- You can also see the line number if you put your cursor in the source code and look at the bottom of the screen. Firefox shows you the line and column of your cursor.