Adding margin-left on a responsive theme without ruining it on mobile

I have installed a responsive wordpress theme and I’m trying to align my title and two columns perfectly.

I have done so by adding margin-left to my columns (I tried it in both pixels and percentage), but then my columns will go off-screen on mobile.

Can I get some tips on this?

The only possible solution I know and haven’t tried is by adding:「@media screen and (max-width: px) 」to my #div’s, but then I don’t know what to set my max-width to and how many variations I should have because I have no experience in customizing responsive theme. So any tip would be helpful.