index.jade

.big-wrapper
  .notice
    pre
      code vertical-align: middle
      br
      | for IE 7+

style
  :stylus
    .big-wrapper
      margin auto
      width 100%
      height 100%
      outline 1px solid skyblue
      background-color #f8f8f8
      color #333
      text-align center
      &:before
        display inline-block
        height 100%
        vertical-align middle
        content '\0020'
      .notice
        display inline-block
        vertical-align middle
        width 200px
        background-color rgba(0, 0, 0, .88)
        padding 10px
        color #f8f8f8

online demo with minor tweak: http://jsfiddle.net/f5U3G/