By default the bottom margin of the <hr> tag is 1px smaller than the top margin. This results through the default $hr-border-width: 1px; setting. If you change $hr-border-width to another value the margin-bottom still remains the same. This fix resolves this issue, so the bottom margin respond to the $hr-border-width value.
border: $hr-border-style $hr-border-color;
border-width: $hr-border-width 0 0;
clear: both;
- margin: $hr-margin 0 ($hr-margin - rem-calc(1));
+ margin: $hr-margin 0 ($hr-margin - em-calc(strip-unit($hr-border-width)));
height: 0;
}