Firefox add-on that embiggens monospaced font in Safaribooksonline.
To use: download the .xpi file, then in Firefox goto Tools > Add-ons, click on the gear icon (Tools for all Add-ons ) and select > Install Add-on from File... then navigate to downloaded .xpi, press Open and Firefox will install the add-on.
Targets the <kbd> element, which is usually set in ems. Does not target monospaced, hyperlink text.