Spaces are invisible in the translation interface

Example for context.

When I translated that string in the web interface I did not notice that it ended with a space. I have an idea that might solve the issue:

Using PHP to detect whether or not the string begins and/or ends with whitespace, give the original string a class such as and a corresponding CSS rule to indicate:

<p class="original whitespace-at-end">Level: </p>

A regex like this ought to do it:

(^\s)|(\s$)