2 column checkout page

Hi!

I’m trying to configure a two column checkout page, I manage to achieve a part of it, but I can’t get the two columns to get next to each other and to get the “Coupon” part in the first column too (“¿Tienes un cupón?”). This is the actual code:

.woocommerce-checkout .col1-set {
float: right;
width: 48%;
}

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

#order_review_heading,
.woocommerce-checkout-review-order {
float: right;
width: 48%;
}

#customer_details .col-1{
width: 48%;
float: left;
}

.woocommerce-page .checkout .col-1,
.woocommerce-page .checkout .col-2 {
width: 100%;
}

Any ideas?

Thank you in advance!