Help finding line of code in WordPress CSS Editor

Hello!

I am trying to edit a line of code via the CSS Editor, however, I can’t seem to locate it. Since I am new to WordPress, I thought maybe I am missing something.

When using Firebug, it tells me that the line of code is here:
/testwp/ #4 (line 647)

Where would I find that?

The code that I am trying to edit is:
#wrapper .post-content h2, #wrapper .fusion-title h2, #wrapper #main .post-content .fusion-title h2, #wrapper .title h2, #wrapper #main .post-content .title h2, #wrapper #main .post h2, #wrapper #main .post h2, #wrapper .woocommerce .checkout h3, #main .portfolio h2 {
font-size: 18px;
line-height: 27px;
}

Thank you in advance for your assistance.