Specify line-height for code in terms of rem
Specify line-height for code in terms of rem

We currently see 1px horizontal lines that originate from some <tr>s
being 17px instead of 16px. Apparently changing line-height to use `rem`
instead of a multiplier fixes the issue.

Change-Id: I4eec06f6fb02cf344e4ced1a6087810b3fa6512a
(cherry picked from commit 2b092152397c6fe06a75260627ddc861ebfc0d6a)

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