asp.net - Re-allignment of panels CSS -


i have 4 panels in page. @ time (depending on conditions ) either 1,2,3 or 4 panels displayed. want panels re-align there no empty space panels not present.

how can ?

edit : if panels visible : http://ibin.co/1zrkoffexnrz

if suppose pannel 3 hidden : http://ibin.co/1zrkco4vtjhw

.container {    display: -webkit-box;    display: -webkit-flex;    display: flex;    -webkit-flex-flow: row;    justify-content: space-around;    padding: 0;    margin: 0;    list-style: none;  }     .rowitem {       background: #ff0000;    padding: 2px;    width: 50%;    height: 50px;    margin-top: 6px;    line-height: 50px;    text-align: center;    font-weight: bold;    border: 1px solid #fff;    }
<ul class="container">    <li class="rowitem">01</li>    <li class="rowitem">02</li>    <li class="rowitem">03</li>    <li class="rowitem">04</li>      </ul>