body {
    padding: 50px;
    font: 14px "Lucida Grande", Helvetica, Arial, sans-serif;
}

.card {
    float: left;
    margin: 10px;
    border: 3px solid #e3e3e3;
    width: 300px;
}

.post-img {
    width: 300px;
}

.mine {
    background-color: #808B96 ;
}

.other {
    background-color: #BFC9CA;
}

.system {
    text-align: center;
}