@mixin form-submit-wrapper() {
     @include span(18 of 18 no-gutters);
     text-align: center;
     padding: 2 * gutter();
}

@mixin form-fields-wrapper() {
   @include span(18 of 18 no gutters);
   padding: gutter();   
}

@mixin form-label() {
  display: block;
  font-weight: 600;
  margin-left: 0;
  margin-bottom: $small-spacing / 2;
}

@mixin form-submit-wrapper() {
  text-align: center;
}

@mixin form-submit-wrapper() {
     @include span(18 of 18 no-gutters);
     text-align: center;
     padding: 2 * gutter();
}

@mixin form-fields-wrapper() {
   @include span(18 of 18 no gutters);
   padding: gutter();   
}

@mixin form-label() {
  display: block;
  font-weight: 600;
  margin-left: 0;
  margin-bottom: $small-spacing / 2;
}

Remove duplicate form-submit-wrapper sass mixin
Remove duplicate form-submit-wrapper sass mixin
