body {
    font-family: Arial, Helvetica, sans-serif;
}
h1 {
    text-align:center;
}
.app h2 {
    margin:0;
    padding:0;
    background:black;
    color:white;
    padding:5px;
    margin-bottom:5px;
}
.app {
    display:inline-block;
    float:left;
    width:calc( 33% - 20px );
    vertical-align: top;
    border:1px solid #cccccc;
    margin:5px;
    padding:5px;
    min-width:400px;
}