Fix inverted diff line highlighting in dark theme
Fix inverted diff line highlighting in dark theme

Signed-off-by: Justin Sleep <0ce7911e6479995d6c346d6f03eb723b5135309e@midnightmechanism.com>

matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk