body {
    font-family: Arial, sans-serif;
    background-color: #f4f4f4;
    text-align: center;
    margin: 0;
    padding: 0;
    user-select: none;
}

.container {
    margin: 50px auto;
    width: 80%;
}

table {
    margin: 20px auto;
    border-collapse: collapse;
}

.hidden {
    display: none;
}


th, td {
    border: 2px solid #333;
    padding: 15px;
    text-align: center;
    width: max(90px, 13vh);
    height: max(90px, 13vh);
    cursor: pointer;
    transition: all 0.3s;
}

td:focus:not(.selected) {
    background: yellow;
}

.selected {
  background: pink;
  font-weight: 600;
  border-radius: 50%;
  background-clip: content-box;
}

h1 {
    color: #333;
}

button {
    padding: 10px 20px;
    font-size: 16px;
    cursor: pointer;
}

form {
    margin-bottom: 20px;
}