body {
  font-family: "Segoe UI", sans-serif;
}

html,
body {
  height: 100%;
}

td,
th {
  border-style: solid;
  font-size: 5mm;
}

input[type="checkbox"] {
  display: none;
}

input[type="checkbox"] + label {
  display: inline-block;
  width: 100%;
  height: 100%;
  text-align: center;
  font-size: 5mm;
}

input[type="checkbox"]:checked + label {
  display: inline-block;
  background: #808080;
  width: 100%;
  height: 100%;
  text-align: center;
  font-size: 5mm;
}