div {
        border: 1px solid;
    }
    #container {
        background-color: lightgreen;
        overflow:auto;
    }
    #title {
        background-color:lightblue;
        margin: 5%;
    }
    .article {
        background-color:white;
        width:50%;
        float:left;
    }
    img {
        width:300px;
    }
    #listTitle {
        width: 400;
        background-color:yellow;
    }
    .group {
        
        width: 100px;
        display:inline-block;
        background-color: lightblue;
        text-align: center;
        margin: 5px;
    }

@media screen and (max-width:549px) {
    img {
        display: inline-block;
        width: 250px;
    }
    .group {
        background-color: red;
    }
}