body, html {
    margin: 0;
    padding: 0;
}

.main {
    max-width: 700px;
    margin: 0 auto;
    overflow: hidden;
}

.content {
    width: 100%;
    padding:20px;
}

@media screen and (max-width: 700px) {
    .sidebar, .content-inner, .content {
        float: none;
        width: 100%;
        margin-right: 0;
    }
}