Hi Vijay,
You can find a lot about CSS online, since it is very wildly used. So I'd recommend you search for this (see for instance a relevant result below), or ask CSS questions on Stack Overflow. And of course, feel free to ask Orbeon Forms specific questions here, or on Stack Overflow with the `orbeon` tag.
https://stackoverflow.com/questions/2032652/how-do-i-get-an-html-text-area-with-monospaced-text-using-cssAlex
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