style.css

.woocommerce .col2-set, .woocommerce-page .col2-set {
  width: 48%;
  float: left;
}

.woocommerce .col2-set .col-1, .woocommerce-page .col2-set .col-1 {
  width: 100%;
}

div#order_review {
  float: right;
  width: 48%;
}

#order_review_heading {
  padding-top: 0;
  float: right;
}