Generated by SassMeister.com.

SassMeister-input.scss

// ----
// libsass (v3.2.5)
// ----

$width: 300;           // desired grid width in px (do not enter 'px')
$fs: 18;                // base font size in px (do not enter 'px')
$const: 1.61803398874;  // Line height constant
$fsconst: 1.165;        // Font size growth constant

// DO NOT CHANGE ANYTHING BELOW
// ----------------------------

@function power ($x, $n) {
    $ret: 1;
    
    @if $n >= 0 {
        @for $i from 1 through $n {
            $ret: $ret * $x;
        } 
    } @else {
        @for $i from $n to 0 {
            $ret: $ret / $x;
        }
    }
    
    @return $ret;
}

@function nearestEven($number) {
    $even: round($number);
    $test: $even % 2; 
    
    // Number is not even, return next even number
    @if ($even % 2 != 0) {
      @return ($even + 1);
    } 
    
    // Number is even - return it
    @return $even;
}

$lh: $fs * $const;

@function calcMediaWidth($width, $fontSize, $constantLineHeight) {
    $calcLineHeight: nearestEven(heightBaseline($fontSize, $fontSize, $const)); 
    $calcWidth: floor($width / $calcLineHeight);
    
    @if ($calcWidth > $width) {
        @return ($calcWidth - 1);
    }
    
    @return $calcWidth;
}

@function heightBaseline($sizePx, $basePx, $baseRatio) {
    $calcBaseline: round($basePx * $baseRatio); // $unit is rounded as well
    
    @return nearestEven((floor($sizePx / $calcBaseline) + 1) * $calcBaseline);
}

/* Grid result calculation */
$unit: heightBaseline($fs, $fs, $const) * 1px;
$grids: calcMediaWidth($width, $fs, $const);

@print {
  base-font-size: $fs * 1px;
  constant: $const;
  line-height: $unit;
  grid-max-columns: $grids;
  desired-grid-width: $width * 1px;
  optimal-grid-width: $unit * $grids;
  

  /****************** 
    Basic font sizes 
   ******************/
  p: $fs * 1px;
  h6: round($fs * power($fsconst, 1)) * 1px;
  h5: round($fs * power($fsconst, 2)) * 1px;
  h4: round($fs * power($fsconst, 3)) * 1px;
  h3: round($fs * power($fsconst, 4)) * 1px;
  h2: round($fs * power($fsconst, 5)) * 1px;
  h1: round($fs * power($fsconst, 6)) * 1px;
}

SassMeister-output.css

/* Grid result calculation */
@print {
  base-font-size: 18px;
  constant: 1.61803;
  line-height: 30px;
  grid-max-columns: 10;
  desired-grid-width: 300px;
  optimal-grid-width: 300px;
  /****************** 
    Basic font sizes 
   ******************/
  p: 18px;
  h6: 21px;
  h5: 24px;
  h4: 28px;
  h3: 33px;
  h2: 39px;
  h1: 45px;
}