body {

    background:#ccc;

    font-family: Verdana, Geneva, Tahoma, sans-serif;
    overflow-y: hidden;
     overflow-x: hidden;
}

.wrapper {

    width: 900px;

    margin: 0 auto;

    background: #fff;
    
    border:1px black dotted;

    padding:1px;
}

header, section, aside {

    border: 1px #000 solid;

    padding: 10px;

}

section {

    width: 540px;

    float: left;

}



aside {

    width: 310px;

    float: right;

}



nav ul {

    margin: 6px;

    padding: 0;

}



nav ul li {

    border: 1px #ccc solid;

    list-style: none;

    display: inline-block;

    padding: 10px;

    background: rgb(0, 255, 170);

    font-weight: 700;

    color: #fff;
    overflow: hidden;
}



nav ul li a {

    color:gold;

    text-decoration: none;
    overflow: hidden;
}

nav ul li:hover {

    background:blue;

}



.videos {

    width: 100%;

}