html, body {
    height: 100%;
    width: 100%;
    margin: 0px;
    padding: 0px;
    top: 0;
    left: 0;
    user-select: none; /* supported by Chrome and Opera */
    -webkit-user-select: none; /* Safari */
    -khtml-user-select: none; /* Konqueror HTML */
    -moz-user-select: none; /* Firefox */
    -ms-user-select: none; /* Internet Explorer/Edge */
}