Faça uma borda tracejada personalizada com SASS

//custom dashed border
@mixin dashed-border($dashlength, $spacelength, $borderwidth, $color, $position: top) {
    $per: percentage($dashlength / ($dashlength + $spacelength));
    background-image: linear-gradient(to right, $color 0%, $color $per, rgba(0, 0, 0, 0) $per);
    background-position: 0 $position;
    background-size: ($dashlength + $spacelength) $borderwidth;
    background-repeat: repeat-x;
}