About vertical_rhythm and adjust margin

[ivan mejia fabela]

I want to know if the way im doing a adjust is correct.

Im Working with vertical_rhythm so add this:

/* Fonts size and line height defaults */

$base-font-size: 16px; /* Sets the browser default size. */

$base-line-height: 24px; /* Baseline grid. */

@include establish-baseline; /* "This is where the magic happens" —Everyone on MTV Cribs. */

Then I want to adjust the vertical margin in some element like this one:

h3 {

  

  

font-weight:500;

  @include adjust-font-size-to(26px); 

  margin: rhythm(1, 56px) 0 0 0; /* 2 line above, 1 line below */

}

What I dont understand is:

 why I need to increase the px to reduce space in margin?