padding-bottom: 1px; of .comment and margin: 1px 0 0 0; of .comment-text are causing this. Or was it intentional that the background is shining through this way?
Bug 1518216 Comment 6 Edit History
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padding-bottom: 1px; of .comment and margin: 1px 0 0 0; of .comment-text are causing this. If you uncheck both, things look consistent. Or was it intentional that the background is shining through this way?