Reduce whitespace importance on reviewable

reduce-whitespace-importantance.css

.diff.line.base:not(.keep) .line.wrapper:not(.empty) .left.line.content,
.diff.line.whitespace:not(.keep) .line.wrapper:not(.empty) .left.line.content {
  background-color: #FFF7F7;  /* rgba(91, 220, 114, 0.05) on white */
}
.diff.line.base .left.line.content .delta, .diff.line.whitespace .left.line.content .delta {
  background-color: rgba(240, 92, 92, 0.05);
}
.one.column.diff .diff.line.base .left.line.content .delta,
.one.column.diff .diff.line.whitespace .left.line.content .delta {
  background-color: rgba(240, 92, 92, 0.15);
}

.diff.line.base:not(.keep) .line.wrapper:not(.empty) .right.line.content,
.diff.line.whitespace:not(.keep) .line.wrapper:not(.empty) .right.line.content {
  background-color: #EFFCF1;  /* rgba(91, 220, 114, 0.05) on white */
}
.diff.line.base .right.line.content .delta, .diff.line.whitespace .right.line.content .delta {
  background-color: rgba(91, 220, 114, 0.05);
}
.one.column.diff .diff.line.base .right.line.content .delta,
.one.column.diff .diff.line.whitespace .right.line.content .delta {
  background-color: rgba(91, 220, 114, 0.15);
}