body {
    background-color: darkgray;
} 
table {
        table-layout: fixed;
        border: 1px solid black;  
        border-spacing: 0;
        width: 50%;
        position: absolute;
        top: 50%;
        left: 50%;
        margin-right: -50%;
        transform: translate(-50%, -50%);
 }

td {
     border: 1px solid black; 
     font-size: 3.125vw;
     font-family: serif;
     font-style: italic;
     font-weight: bold;
     width: 6.25vw;
     height: 6.25vw;
     text-align: center; 
     vertical-align: middle;
}
/*
td::after {
  content: '';
  display: block;
  margin-top: 100%;
}

td .content {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
}
*/

tr:nth-child(even) td:nth-child(even),
tr:nth-child(odd) td:nth-child(odd)
 {color: black; background: white;}

tr:nth-child(even) td:nth-child(odd),
tr:nth-child(odd) td:nth-child(even)
 {color: white; background: black;}