Setting margins and paddings

[fluxxus]

Full disclosure; new to Sass and currently in the process of getting to know typography a lot better.

So, if I want to keep a consistent vertical rhythm, this is how I set my margins/paddings ?

margin-bottom: emRhythm(5)

Just a few quick questions more.

I see a variable called $base-line-multi, what is it its purpose and how can it be used ?

Can I change the modular scale ratio to some other ?

I don't quite get the logic behind the emRhythm function.

.test {
  margin-bottom: emRhythm(4, $ms-down1);
}

Shouldn't increasing the ms-down-1 to ms-up4, for example, be resulting in a bigger margin? Yet, the value decreases.

Also, in the source file you provide to see the styles applied to typesettings website, sometimes you use the emRhythm function with just one parameter, and sometimes with $ms-X.

That produces different results, what is the reasoning behind that usage ?

Sorry for all the simple questions !!

[fluxxus]

Figured it out all by myself, by playing with your source files for the demo page.