Here's a handy little tip if you are using the plugin Crayon Syntax Highlighter to display snippets of code on your WordPress site.
It's possible to mark particular lines as important so they appear highlighted.
If you are manually inserting the <pre> tag into your post, just give it a class with the following attribute:
This will highlight line 1 and lines 4-7 inclusive.
Alternatively, if you are using the Crayon 'Add Code' button in the visual editor, use the 'Marked Lines' field in much the same way:
For more information about Crayon and the different attributes that can be used in the tag, see this great Crayon Readme on Packagist.