Refer to PowerShell Active Directory Browser
Backticks are incorrectly interpreted as some sort of string, instead of a line continuation character.
We don't have a PowerShell syntax highlighter, because Google Prettify doesn't have a PowerShell plugin. What you see is the "best guess one-size-fits-all" default highlighter trying its best. There's an open issue request on Prettify that includes a plugin, but it's only a partial implementation. I'd be happy to include the PowerShell highlighter when it's complete, but until then the default highlighter (or alternatively no highlighting at all) is all we have.