add margin around buttons so they don't shit the bed when wrapping

BS3 commit 8e8fe8de93b1d25273dcabe348e2d9205a428037
fix copypasta-o to fully fix 9295

BS3 commit 3a67054536338c613c43078b6f48e5f502bf527d
minor change
add callout about browser zooming to browser support section

BS3 commit 083b7c0981656ff1c660482653645bb9e4f71543
more accurate grid table breakpoint numbers

BS3 commit 70b0fb445ee373811ea952a0936493c4f574fba2
add grid docs about responsive column clearing

BS3 commit 6e26f846cdb96060afb0530f1d34fdfc2a11f83d
fix inaccurate comment in media query docs

BS3 commit c84d34b5f1ae6908c5a0b524c17b81103b831f35
fixes 9522

BS3 commit f058a6a3ea6196af859303ff4611fd9807842f7d