Simple CSS FLEX Stretch to Width

HTML

<body>
    <div id="wrapper">
        <div class="center"></div>
    </div>
</body>

CSS

#wrapper {
     margin:0;
     padding:0;
     width:10000px;
     position:absolute;
     height:100%;
     bottom:0;
     background-color: #66CC33;
     -webkit-flex-direction: stretch;
     -moz-flex-direction:stretch;
     flex-direction: stretch;
     display: -webkit-flex;
     display: -moz-flex;
     display: flex;
 }
 .center {
     -webkit-flex-direction: column;
     -moz-flex-direction:column;
     flex-direction: column;
     display: -webkit-flex;
     display: -moz-flex;
     display: flex;
     width: 100%;
     height:390px;
     margin:5px;
     border-radius: 5px;
     background-color: #CC3399;
 }