main {
    background: #ff0;
    display: table;
    width: auto;
    width: 100%;
}

.bar {
    width: auto;
    width: 100%;
    float: left;
    display: table;
    margin-right:1%;
}

.spalte50 {
    width: auto;
    width: 49%;
    float: left;
    display: table;
    margin-right:1%;
}

.picture {
    width: auto;
    width: 100%;
}

@media only screen and (max-width: 400px) {
    .spalte50 {
        width:100%;
    }
}