#myBtn {
    display: none;
    /* Hidden by default */
    position: fixed;
    /* Fixed/sticky position */
    bottom: 20px;
    /* Place the button at the bottom of the page */
    right: 10px;
    /* Place the button 30px from the right */
    z-index: 99;
    /* Make sure it does not overlap */
    border: none;
    /* Remove borders */
    outline: none;
    /* Remove outline */
    background-color: black;
    /* Set a background color */
    color: white;
    /* Text color */
    cursor: pointer;
    /* Add a mouse pointer on hover */
    padding: 15px;
    /* Some padding */
    border-radius: 10px;
    /* Rounded corners */
    font-size: 18px;
    /* Increase font size */
}

#myBtn:hover {
    background-color: #555;
    /* Add a dark-grey background on hover */
}



.arrow {
    border: solid white;
    border-width: 0 3px 3px 0;
    display: inline-block;
    padding: 3px;
}



.up {
    transform: rotate(-135deg);
    -webkit-transform: rotate(-135deg);
}