@media screen and (min-width: 900px) {
    .header{
    background-color: lightgray;
    padding: 1%;
    }
    .menu{
    background-color: black;
    overflow: hidden;
    margin: 0;
    padding: 0;
    margin-top: 1%;
    }

    .menu ul{
    padding-left: 0;
    }

    .menu ul li{
        list-style-type: none;
        display: inline;
        padding: 0;
        margin: 0;
    }

    .menu ul li a{
        text-decoration: none;
        color: whitesmoke;
        padding: 14px 16px;
        border-right: 2px solid;
        margin: 0;
    }

    .menu ul li a:hover{
        background-color: grey;
        transition: 1s;
    }

    .content{
        margin: 1%;
        display: flex;
    }

    .leftbox ul{
        list-style: none;
        width: 100px;
        margin: 0;
        padding: 0;
    }

    .leftbox ul li {
        margin-bottom: 10PX;
    }

    .middlebox{
    width: 60%;
    margin-right: 1%;
    margin-left: 1%;
    }

    .rightbox{
        width: 40%;
    }

    .footer{
        clear: both;
        text-align: right;
        padding: 1%;
        background-color: lightgray;
    }
}

@media screen and (max-width: 900px) {
    .header{
    background-color: lightgray;
    padding: 1%;
    }
    .menu{
    background-color: black;
    overflow: hidden;
    margin: 0;
    padding: 0;
    margin-top: 1%;
    }

    .menu ul{
    padding-left: 0;
    }

    .menu ul li{
        list-style-type: none;
        display: inline;
        padding: 0;
        margin: 0;
    }

    .menu ul li a{
        text-decoration: none;
        color: whitesmoke;
        padding: 14px 16px;
        border-right: 2px solid;
        margin: 0;
    }

    .menu ul li a:hover{
        background-color: grey;
        transition: 1s;
    }

    .content{
        margin: 1%;
    }

    .leftbox ul{
        list-style: none;
        width: 100px;
        margin: 0;
        padding: 0;
        margin-left: 1%;
    }

    .leftbox ul li {
        margin-bottom: 10PX;
    }

    .middlebox{
    width: 60%;
    margin-right: 1%;
    margin-left: 1%;
    }

    .rightbox{
        width: 40%;
        margin-left: 1%;
    }

    .footer{
        clear: both;
        text-align: center;
        padding: 1%;
        background-color: lightgray;
    }
}