Remove space between age value and unit.
Add subreddit link to header.
Scroll to top when viewing a comment thread.
Fix styles for selected comment with no children.

A selected element with no children was still getting top and bottom
borders on the children container element, which appeared as a random
line.  Also removed the bottom margin.
Make the word 'reddit' in header clickable.
Update styling of OP comments.
Fix margin on reply icon and add title attribute.
Temporarily hide 'more-comment' elements.

These don't do anything at the moment anyway.