/* fullscreen class for code element */
pre code.fullscreen{
    z-index: 9999;
    width: 100%;
    height: 100%;
    position: fixed;
    top: 0;
    left: 0;
    background-color: red;
}
pre {
    position: relative;
}
pre code {
    position: relative;
}
pre .fullscreen-button{
    z-index: 1;
    position: absolute;
    top: 0;
    right: 0;
}
/* additional box */
div#fullscreen-box {
    margin: 0;
    padding: 0;
    z-index: 9999;
    position: absolute;
    top: 0;
    right: 0;
    width: 100%;
    height: 100%;
    display: none;
}
div#fullscreen-box pre,
div#fullscreen-box code {
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100%;
}
div#fullscreen-box pre{
    overflow: hidden;
}
div#fullscreen-box pre code{
    overflow: auto;
}
div#fullscreen-box.visible{
    display: block;
}