.text{margin-top:10px;white-space:pre-wrap;text-align:justify;text-justify:inter-word}.derivation-tree{display:flex;flex-direction:column;align-items:center;text-align:center;margin-bottom:10px}.children{display:flex;justify-content:space-around;width:100%;align-items:flex-end}.child{margin:0 10px}.subtree-rule{display:flex}.subtree{position:relative}.rule{cursor:pointer;color:blue;text-decoration:underline}.rule,.rule-text{margin-left:10px;position:relative}