Update to _defaults

Typographical changes:

/* Variables */

/* Primary Font Faminly */
$primary-font-sans: 'Lato', sans-serif;

/* Secondary Font Faminly */
$secondary-font-sans: 'Raleway', sans-serif;

/* Basic Font Sizes mixin */
@mixin font-size($sizeValue: 1.6) {
  font-size: ($sizeValue * 10) + px;
  font-size: $sizeValue + rem;
}