h2 {
  background: blueviolet;
  text-align: center;
  padding: 10px;
  border: 1px solid blue;
}

body {
  font-family: Verdana, Geneva, Tahoma, sans-serif;
  margin-left: 20px;
  margin-right: 20px;
}

table {
  width: 100%;
}

td {
  padding: 10px 20px;
  border-top: 1px solid lightgray;
  border-left: 1px solid lightgray;
  border-bottom: 1px solid darkgray;
  border-right: 1px solid darkgray;
}

.error {
  background-color: orange;
  color: red;
  padding: 5px;
  margin: 20px 50px;
  border: 1px solid red;
}

.hightlight {
  background: yellow;
}

a {
  color: blue;
}

td label {
  cursor: pointer;
}

form {
  margin: 5px;
  padding: 5px;
  color: blue;
}

#instructions {
  display: none;
  border: 1px solid blue;
  margin: 10px;
  padding: 20px;
}

table td.crossed {
  background-image: linear-gradient(to bottom right, transparent calc(50% - 2px), black, transparent calc(50% + 2px));
}