html,
body {
  height: 100%;
  background-color: #000030;
}
body {
  color: #fff;
  text-align: center;
  text-shadow: 0 1px 3px rgba(0,0,0,.5);
}

.site-wrapper {
  display: table;
  width: 100%;
  height: 100%; /* For at least Firefox */
  min-height: 100%;
  -webkit-box-shadow: inset 0 0 100px rgba(0,0,0,.5);
          box-shadow: inset 0 0 100px rgba(0,0,0,.5);
}
.site-wrapper-inner {
  display: table-cell;
  vertical-align: top;
}
.cover-container {
  margin-right: auto;
  margin-left: auto;
}

/* Padding for spacing */
.inner {
  padding: 30px;
}

.cover {
  padding: 0 20px;
}
.cover .btn-lg {
  padding: 10px 20px;
  font-weight: bold;
}

@media (min-width: 768px) {
  .site-wrapper-inner {
    vertical-align: middle;
  }
  .cover-container {
    width: 100%; /* Must be percentage or pixels for horizontal alignment */
  }
}

@media (min-width: 992px) {
  .cover-container {
    width: 700px;
  }
}