<div class="container">
    <h1>Checkout Form</h1>
    <form class="form cf">
      <section class="plan cf">
        <h2>Choose a plan:</h2>
        <input type="radio" name="radio1" id="free" value="free"><label class="free-label four col" for="free">Free</label>
        <input type="radio" name="radio1" id="basic" value="basic" checked><label class="basic-label four col" for="basic">Basic</label>
        <input type="radio" name="radio1" id="premium" value="premium"><label class="premium-label four col" for="premium">Premium</label>
      </section>
      <section class="payment-plan cf">
        <h2>Select a payment plan:</h2>
        <input type="radio" name="radio2" id="monthly" value="monthly" checked><label class="monthly-label four col" for="monthly">Monthly</label>
        <input type="radio" name="radio2" id="yearly" value="yearly"><label class="yearly-label four col" for="yearly">Yearly</label>
      </section>
      <section class="payment-type cf">
        <h2>Select a payment type:</h2>
        <input type="radio" name="radio3" id="credit" value="credit"><label class="credit-label four col" for="credit">Credit Card</label>
        <input type="radio" name="radio3" id="debit" value="debit"><label class="debit-label four col" for="debit">Debit Card</label>
        <input type="radio" name="radio3" id="paypal" value="paypal" checked><label class="paypal-label four col" for="paypal">Paypal</label>
      </section>  
      <input class="submit" type="submit" value="Submit">   
    </form>
  </div>

body{
  margin: 0;
  padding: 0;
  font-family: sans-serif;
  color: #333;
  background-color: #eee;
}

h1, h2, h3, h4, h5, h6{
  font-weight: 200;
}

h1{
  text-align: center;
  padding-bottom: 10px;
  border-bottom: 2px solid #2fcc71;
  max-width: 40%;
  margin: 20px auto;
}

/* CONTAINERS */

.container {max-width: 850px; width: 100%; margin: 0 auto;}
.four { width: 32.26%; max-width: 32.26%;}


/* COLUMNS */

.col {
  display: block;
  float:left;
  margin: 1% 0 1% 1.6%;
}

.col:first-of-type { margin-left: 0; }

/* CLEARFIX */

.cf:before,
.cf:after {
    content: " ";
    display: table;
}

.cf:after {
    clear: both;
}

.cf {
    *zoom: 1;
}

/* FORM */

.form .plan input, .form .payment-plan input, .form .payment-type input{
  display: none;
}

.form label{
  position: relative;
  color: #fff;
  background-color: #aaa;
  font-size: 26px;
  text-align: center;
  height: 150px;
  line-height: 150px;
  display: block;
  cursor: pointer;
  border: 3px solid transparent;
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
}

.form .plan input:checked + label, .form .payment-plan input:checked + label, .form .payment-type input:checked + label{
  border: 3px solid #333;
  background-color: #2fcc71;
}

.form .plan input:checked + label:after, form .payment-plan input:checked + label:after, .form .payment-type input:checked + label:after{
  content: "\2713";
  width: 40px;
  height: 40px;
  line-height: 40px;
  border-radius: 100%;
  border: 2px solid #333;
  background-color: #2fcc71;
  z-index: 999;
  position: absolute;
  top: -10px;
  right: -10px;
}

.submit{
  padding: 15px 60px;
  display: inline-block;
  border: none;
  margin: 20px 0;
  background-color: #2fcc71;
  color: #fff;
  border: 2px solid #333;
  font-size: 18px;
  -webkit-transition: transform 0.3s ease-in-out;
  -o-transition: transform 0.3s ease-in-out;
  transition: transform 0.3s ease-in-out;
}

.submit:hover{
  cursor: pointer;
  transform: rotateX(360deg);
}