remove space between left sidebar and main content, 2014

I have made a child theme of twentyfourteen. There is too much space between the left sidebar (“secondary”) and the main content for my taste. But with the responsive design, there are many special cases (e.g. @media screen and (min-width: 1080px)). Do I need to go through each of those cases and provide detailed css changes, or is there a more elegant way?

If there’s a good article out there that discusses this, please provide a link and I’ll read up on this. Maintaining the responsiveness is important to me. Thank you.