pre {
  background: midnightblue;
  color: white;
  width: 80ch;
  padding: 1ch;
  margin-left: 3em;
}

code {
  background: silver;
  padding: 0.5ch;
}

.calc {
  font-size: 200%;
  margin-left: 1em;
  color: black;
  background: silver;
  width: 16ch;
  border: 1px solid;
}

table {
  border-collapse: collapse;
  border: 1px solid black;
}

td {
  padding-left: 1em;
  padding-right: 1em;
}