The CSS media type “print” allows authors to specify a stylesheet that is only used when printing. This can be very useful and allows for neatly styled printouts that hide non-essential parts of the page and only contain the main content. It’s a great concept.
To achive this, create a separate stylesheet say, print.css, and put your classes there in the css file. Apply the classes to the fields you want to customise while printing and then add the following in your page's head section.
<link rel="Stylesheet" href="../Style/print.css" media="print" type="text/css" />
Note: This will only apply when someone is printing the page.
Give it a try!!