None of the available fonts in the content editor, nor Syntax Highlighting, are a reliable solution to display code among different web browsers and OS platforms. Some rely on New Courier to display code, but it does a poor job to distinguish between 1 and lowercase L, depending on font size and platform.
How does the above compare to what you see below?
The editor offers fonts in the pull-down menu which are not available on all platforms and do not display correctly. Andale Mono, while still bundled with MacOS/X, is no longer distributed with Microsoft Windows. Microsoft replaced Andale Mono with Lucida Console starting with Windows ME nearly 20 years ago. Lucida Console is the default font for Windows Powershell.
Andale Mono and Lucida Console are not the best available fonts to display code and are not standard on all OS platforms. You can install Andale Mono for MS Windows, but it doesn't look pretty. Lucida Console, on the other hand, ships with MS Office for Mac, and is also available for Linux.
A dynamic web font for code, which gets downloaded when accessing the platform might be the best solution, but in the meantime, I suggest to modify the drop-down menu in the rich text editor and replace Andale Mono with Lucida Console.