Susy grid same height

Question

I have this susy grid and I would like to have all its columns the same height, I tried adding the display: table technique but I can't get it to work. I tried the suggestions posted in here but that didn't get me anywhere either, I created this codepen to see if someone can take a look.

@import "susy";

$susy: (
  columns: 12,
  gutters: 0,
);

.container{
  @include container(600px center);
}
.mTable {
  display:table;
  > .col {
 @include span(6);
    display:table-cell;
    &:nth-child(odd){
    background-color:gray;
  }
    &:nth-child(even){
    background-color:lightgray;
  }
  }
  
}