#edit-group {
  position: fixed;
  top: 0;
  left: 0;
  background-color: #f4f4f4;
  width: 100%;
  height: 100%;
  z-index: 10;
}

#edit-group form {
  /* 5rem is the height of the header */
  height: calc(100% - 5rem);
  padding: 0 1.5rem;
}

#edit-group form p {
  width: 100%;
  margin-top: 10rem;
}