.prebox{
  background: rgba(255,255,255,0.04);
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: 12px;
  padding: 12px;
  overflow: auto;
  max-height: 420px;
  font-size: 0.9rem;
  line-height: 1.35;
}

textarea.form-control{
  resize: vertical;
}