tton" onclick="zoomIn()" aria-hidden="true"></i>
    <i id="zoomOutButton" class="fa fa-search-minus button" onclick="zoomOut()" aria-hidden="true"></i>
    <div id="middle-space-toolbar"></div>
    <i id="scrollToTopButton" class="fa fa-angle-double-up button" onclick="scrollToTop()" aria-hidden="true"></i>
    <i id="scrollUpButton" class="fa fa-chevron-up button" onclick="scrollUp()" aria-hidden="true"></i>
    <i id="scrollDownButton" class="fa fa-chevron-down button" onclick="scrollDown()" aria-hidden=