.generate-ls(10);

.generate-ls(@n, @i: 1) when (@i =< @n) {
    .fg-@{i} {
        letter-spacing: ("."+ @i + "rem");
    }

    .generate-ls(@n, (@i + 1));
}

.ls-1 {
    letter-spacing: .1rem;
}

.ls-2 {
    letter-spacing: .2rem;
}

.ls-3 {
    letter-spacing: .3rem;
}

.ls-4 {
    letter-spacing: .4rem;
}

.ls-5 {
    letter-spacing: .5rem;
}

.ls-6 {
    letter-spacing: .6rem;
}

.ls-7 {
    letter-spacing: .7rem;
}

.ls-8 {
    letter-spacing: .8rem;
}

.ls-9 {
    letter-spacing: .9rem;
}

.ls-10 {
    letter-spacing: 1rem;
}