.book-summary ul.summary {
  overflow-y: scroll;
  height: calc(100% - 196px);
  position: absolute;
  width: 300px;
}

.sidebar-addition {
  position:fixed;
  height: 150px;
  width: 300px;
  left: 0;
  bottom: 0;
  background: #fafafa;
  border-top: 1px solid rgba(0,0,0,.07);
  border-right: 1px solid rgba(0,0,0,.07);
  text-align: center;
  display: none;
}

.sidebar-addition img {
  height: 90%;
  margin: 2.5%;
  float: left;
}

.sidebar-addition p {
  line-height: 150%;
  padding: 10px;
  margin: 0 0 10px 0;
}

.sidebar-addition .btn {
  background: rgba(0,0,0,.07);
  color: rgba(0,0,0,0.4);
  padding: 5px 10px;
  border-radius: 4px;
  margin-top: 5px;
}

.with-summary .sidebar-addition {
  display: block;
}