.spacer {
    margin-top: 400px; /* define margin as you see fit */
}
/* image roll over */
.pdf-thumb-box {
  display: inline-block !important;
  position: relative !important;
  overflow: hidden;
}
.pdf-thumb-box-overlay {
  display: none;
}
.pdf-thumb-box a:hover .pdf-thumb-box-overlay {
  display: inline;
  text-align: center;
  position: absolute;
  transition: background 0.2s ease, padding 0.8s linear;
  background-color: rgba(0, 0, 255, 0.58);
  color: #fff;
  width: 100%;
  height: 100%;
  text-shadow: 0 1px 2px rgba(0, 0, 0, .6);
}
.pdf-thumb-box-overlay span {
  position: relative;
  top: 50%;
  -webkit-transform: translateY(-50%);
  -ms-transform: translateY(-50%);
  transform: translateY(-50%);
}
/* end of image roll over */
.top-buffer { 
	margin-top:40px; 
	}