.boxed {
  border: 1px solid #555;
  margin: 3px;
  padding: 5px;
}

.underlined {
  text-decoration-line: underline;
}

div.explain_wrap > div.explain_main {
  display: none;
  overflow: hidden;
}

div.explain_wrap:hover > div.explain_main {
  border: 1px solid #555;
  margin: 3px;
  padding: 5px;
  display: block;
  overflow: hidden;
}

td,th {
    padding: 5px;
}