Edit in JSFiddle

<div class="quote-container">
<div class="group-plan-selection">
        <h2 class="hidden">Choose a plan</h2>
        <ul>
          <li>
            <label class="choose-silver quarter primary selected">
              <span class="corner-tab"></span>
              <h3>Silver Membership</h3>
              <input type="radio" name="plan" checked="" value="280986df" id="silver-radio" class="hidden">
            </label>
          </li>
          <li>
            <label class="choose-gold quarter secondary inactive">
              <span class="corner-tab"></span>
              <h3>Gold Membership</h3>
              <input type="radio" name="plan" value="a38d7ec1" id="gold-radio" class="hidden">
            </label>
          </li>
        </ul>
</div>
</div>

li{list-style-type:none}
.group-plan-selection label{background:#FFF;width:160px;text-align:center;font-size:1em;position:relative;z-index:0;cursor:pointer;-webkit-border-radius:8px;-moz-border-radius:8px;-ms-border-radius:8px;-o-border-radius:8px;border-radius:8px;padding:20px}
.quarter{width:200px;margin-right:30px}
.primary{float:left}
label{margin-bottom:3px;font-size:1.6em;display:inline-block;vertical-align:middle;zoom:1}
.group-plan-selection label .corner-tab{background-position:0 45px;width:45px;height:45px}
.corner-tab{background:#A8ABB3 url(data:image/png;base64,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) -25px -100px;width:75px;height:75px;position:absolute;top:0;left:0;-webkit-border-radius:8px 0 0 0;-moz-border-radius:8px 0 0;-ms-border-radius:8px 0 0 0;-o-border-radius:8px 0 0 0;border-radius:8px 0 0 0}
label span{color:#58902A}
.group-plan-selection h3{font-size:1.4em;margin:0 0 5px}
.group-plan-selection label.choose-gold .corner-tab{background-color:#CEC25A}
.hidden{display:none!important}
.quote-container{background:#E3E3E0;-webkit-border-radius:0 0 5px 5px;-moz-border-radius:0 0 5px 5px;-ms-border-radius:0 0 5px 5px;-o-border-radius:0 0 5px 5px;border-radius:0 0 5px 5px;margin:0;padding:30px}
h1,h2,h3,h4,h5,h6{font-weight:700;letter-spacing:-.03em;color:#33383D;line-height:1.2}
.inactive{opacity:0.3;cursor:default}

$('input:radio').on('change', function() {
    $('.quarter').addClass('inactive');
    var el = $(this);
    $(el.closest('label').get(0)).removeClass('inactive');
});