Hello,
1) There is default margin after the paragraph. If you want to increase the space you can use margin-bottom http://prntscr.com/pdibz3
2) You used header builder to create the header and did not change the bg color for the mobile menu http://prntscr.com/pdicyx Our demo uses a built-in header option (old header), we have not migrated demo to new builder yet. But we are working on it.
Regards