@charset "UTF-8";
@import url("https://fonts.googleapis.com/css?family=Cascadia+Code:400,400i,700");
* {
  box-sizing: border-box;
}

body {
  font-family: "Cascadia Code", monospace;
  font-size: 2vh;
  text-align: center;
}

table {
  border-collapse: collapse;
  border: 1px black solid;
  margin: 0 auto;
}
table td {
  aspect-ratio: 1/1;
  vertical-align: middle;
  text-align: middle;
  border: 1px black solid;
  width: 20vh;
  max-width: 20vh;
  height: 20vh;
  padding: 1vh;
  cursor: pointer;
  position: relative;
}
table td.checked {
  color: rgba(0, 0, 0, 0.5);
}
table td.checked:before {
  content: "×";
  font-size: 20vh;
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  color: red;
  font-weight: bold;
  line-height: 1;
  display: flex;
  align-items: center;
  justify-content: center;
}