You want simpler, STOP USING DOUBLE QUOTES ON PHP STRINGS! :rofl:
... and you can get the spaces to show with a hint of CSS without the container going block-level using white-space: pre, though really PRE by itself should be enough to do what you want.
untrimmed: firstName = "',$_POST['firstName'],'"
trimmed: firstName = "',$trimmed['firstName'],'"
Using single quotes also means white space in the output is preserved, and it only needs ONE echo statement... and the presence of <pre> means your carriage returns show up on the page.