The line numbers won’t show up in WP, most developers use a separate HTML/CSS editor to edit their files through FTP (it’s much safer/faster this way). If you’re using the WP editor, then I guess you could just open up a text editor and copy/paste the code there make the edits and then paste it back in WP. Although I’d highly recommend using an FTP program like filezilla or whatever you prefer.
Just make sure you’re using a text editor designed for HTML/CSS so the lines show up and the format of the css isn’t messed up.
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