Content Max Width when designing?

I am about to design a new webpage in Adobe XD but have some questions that I really would appreciate if someone could help me with:

1. What max-width for the content is used nowdays for desktops? 1366px? 1200px?

2. I will use a 12 grid system for desktops. What gutter width do you recommend? 2%?

Thanks a lot!

from HTML & Website Design http://bit.ly/2WB9XWB
via IFTTT