Merge remote-tracking branch 'richrace/master'
Resolved the problem that the height of the line increase by one pixel when underline is enabled

By default, height of border, padding, and margin is 0, when underline is enabled, the border-bottom set to 1px, then the current line has been  lifted.  Set margin-bottom to -1px can resolve it.

Signed-off-by: Huang Cheng <sniperbat@gmail.com>
Merge pull request #7 from sniperbat/master

Resolved the height of the line increase by one pixel