Edit in JSFiddle

body {
   color: #fff;
   font-family: 'DejaVu Sans Mono','Courier New',monospace;
   font-size: 12px;
}

.c {
    background-color: rgba(164, 0, 0, 0.9);
    color: #fff;
    height: 100px;
    line-height: 100px;
}
.c p {
  position: relative;
  top: 50%;
  -webkit-transform: translateY(-50%);
  -ms-transform: translateY(-50%);
  transform: translateY(-50%);
}

<div class="c">
  <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit.</p>
</div>