inject.css

.rc-dropzone {
  font-family: Helvetica, Arial, sans-serif;
  text-align: center;
  color: white;
  text-transform: uppercase;
  background: #5755d9;
  position: fixed;
  top: 20px;
  right: 20px;
  overflow: hidden;
  width: 36px;
  height: 36px;
  border-radius: 100%;
  z-index: 99999;
}

.rc-dropzone__active {
  background: #4240d4;
  outline: 0;
}

.rc-plusicon {
  font-size: 30px;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -55%);
  vertical-align: middle;
}