html, body { height: 100% } body { margin: 0px; font-size: 40px; } section { display: -webkit-box; display: -webkit-flex; display: -moz-box; display: -ms-flexbox; display: flex; -webkit-box-align: center; -webkit-align-items: center; -moz-box-align: center; -ms-flex-align: center; align-items: center; -webkit-box-pack: center; -webkit-justify-content: center; -moz-box-pack: center; -ms-flex-pack: center; justify-content: center; height: 100%; } h1, h2, h3, h4, h5 { text-align: center; } .note { display: none; } p { text-align: center; } pre { white-space:pre }