help: Remove white border after h1 titles.
help: Remove white border after h1 titles.

This hasn't been part of the visible design for some time; however the
relocation in 3319893545d54a209f35fd2cc6f3392885a589e1 caused these to
appear again.

eeshangarg/zulip,andersk/zulip,rht/zulip,eeshangarg/zulip,andersk/zulip,zulip/zulip,andersk/zulip,andersk/zulip,zulip/zulip,eeshangarg/zulip,andersk/zulip,kou/zulip,andersk/zulip,andersk/zulip,eeshangarg/zulip,eeshangarg/zulip,kou/zulip,zulip/zulip,rht/zulip,rht/zulip,kou/zulip,rht/zulip,kou/zulip,zulip/zulip,kou/zulip,zulip/zulip,eeshangarg/zulip,rht/zulip,eeshangarg/zulip,kou/zulip,rht/zulip,zulip/zulip,kou/zulip,rht/zulip,zulip/zulip