.topnav {
    overflow: hidden;
    background-color: #333;
    position: absolute;
    top: 90px;
    width: 100%;
}

    .topnav a {
        float: left;
        color: #f2f2f2;
        text-align: center;
        padding: 6px 16px;
        text-decoration: none;
        font-size: 17px;
        height: 20px;
    }

        .topnav a:hover {
            background-color: #ddd;
            color: black;
        }

        .topnav a.active {
            background-color: #4CAF50;
            color: white;
        }





.intro {
    float: left;
    color: #f2f2f2;
    text-align: center;
    padding: 6px 16px;
    text-decoration: none;
    font-size: 14px;
    height: 20px;
}




.images {
    
    width: 70%;
    height: 70%;
    display: block;
    margin-left: auto;
    margin-right: auto;
    margin-top: 50px;
}


.button_left {
    position: absolute;
    top: 300px;
    width: 40px;
    height: 80px;
    left: 20px;
    color: white;
    border-color: darkslategray;
    background-color: darkslategray;
    border-color: #303030;
    background-color: #303030;
}

.button_right {
    position: absolute;
    top: 300px;
    width: 40px;
    height: 80px;
    right: 20px;
    color: white;
    border-color: #303030;
    background-color: #303030;
}