モダン？な上下中央揃え

IE8以上とのこと http://hyper-text.org/archives/2014/08/position_absolute_center_layout.shtml

by FiNGAHOLiC

HTML

<div class="test">
 <h1>Absolutely positioned element</h1>
 <p>text...</p>
</div>

CSS

.test {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  margin: auto;
  width: 300px;
  height: 300px;
  background: red;
}