<!-- Top-left corner -->
table tr:first-child th:first-child ,
table tr:first-child td:first-child   { border-top-left-radius     : 15px ; }

<!-- Top-right corner -->
table tr:first-child th:last-child  ,
table tr:first-child td:last-child    { border-top-right-radius    : 15px ; }

<!-- Bottom-left corner -->
table tr:last-child  td:first-child   { border-bottom-left-radius  : 15px ; }

<!-- Bottom-right corner -->
table tr:last-child  td:last-child    { border-bottom-right-radius : 15px ; }