body { overflow: hidden; margin: 0; padding: 0; }

#logo { position: fixed; z-index: 20; top: 20px; left: 20px; width: 200px; }
#logo img { width: 100%; }

#centrarvista { position: fixed; z-index: 40; bottom: 20px; right: 20px; cursor: pointer; }
#centrarvista img { width: 25px; }