$col_margin: 2%;

.ce_gallery > ul > li {
  margin: 0 $col_margin $col_margin;
  float: left;
}
.ce_gallery > ul > li.col_first {
  clear: none;
}

.ce_gallery .cols_1 > li {
  float: none;
}

.ce_gallery > ul > li:first-child {
  width: 100%;
  margin-left: 0;
  margin-right: 0;
  float: none;
}

@for $i from 1 through 12 {
  .ce_gallery > .cols_#{$i} > li:nth-child(1n+2) {
    width: (100-($i * (2 * $col_margin) - (2 * $col_margin))) / $i;
  }
  .ce_gallery > .cols_#{$i} > li:nth-child(#{$i}n+2) {
    margin-left: 0;
    clear: left;
  }
  .ce_gallery > .cols_#{$i} > li:nth-child(#{$i}n+1) {
    margin-right: 0;
  }
}