On a mobile browser you don't seem to have the "like" or the "rep" buttons.
If you really, really, really want to "like" that witty post you COULD request the desktop site. See that button at the top right of your screen that looks like three dots in a vertical row, like this?
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Hit that button and click on "Request desktop site." (At least that's how it works in my Firefox For Android...) You will get the full featured webpage, complete with like and rep buttons.
I would mention that trying to read a post on the full desktop version of the website is difficult. The mobile version of this site is much less cluttered and MUCH easier to read on a phone. After you are done repping and liking I recommend going back to that menu and unchecking "request desktop site." But that's up to you.