body { vertical-align: middle; align: center; background-color: black; color: red; }
.chooser { border: 1px dotted white; font-size: 2em; padding: 1em; color: white; background-color: blue; line-height: 4em; margin: 2em 1em; }
.chooser:hover { border: 1px solid white; }
.centerbox { top: 4em; position: relative; }