@function px-to-em($s, $b: $font-size) {
    @return 1 / ($b / 1px) * ($s / 1px) * 1em;
}

@function str-repeat($s, $n) {
    $r: '';
    @while $n > 0 {
        $r: $r + $s;
        $n: $n - 1;
    }
    @return $r;
}