body {
  background: #ffffff;
}
.block {
  height: 100px;
  overflow: hidden;
  position: relative;
  background: #ffffff;
}
.block.opener {
  height: auto;
}
.block:after {
  content: "";
  width: 100%;
  left: 0;
  position: absolute;
  height: 50px;
  bottom: 0;
  background: -moz-linear-gradient(top,  rgba(255,255,255,0) 0%, rgba(255,255,255,1) 100%);
  background: -webkit-linear-gradient(top,  rgba(255,255,255,0) 0%,rgba(255,255,255,1) 100%);
  background: linear-gradient(to bottom,  rgba(255,255,255,0) 0%,rgba(255,255,255,1) 100%);
  filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#00ffffff', endColorstr='#ffffff',GradientType=0 );
}
.block.opener:after {
  opacity: 0;
}