CSS для таблиц. Игнорирование стиля - Вопросы по CSS

@media screen and (max-width: 600px) {
table {width:100%;}
thead {display: none;}
tr:nth-of-type(2n) {background-color: inherit;}
tr td:first-child {background:; font-weight:bold;}
tr th:first-child {font-weight:bold;}
tbody td, tbody th {display: block; text-align:center;}
tbody td, tbody th:before {
content: attr(data-th);
display: block;
text-align:center;
}
}

@media screen and (max-width: 600px) {
  table:not(.nostyle) {width:100%;}
  table:not(.nostyle) thead {display: none;}
  table:not(.nostyle) tr:nth-of-type(2n) {background-color: inherit;}
  table:not(.nostyle) tr td:first-child {background:none; font-weight:bold;}
  table:not(.nostyle) tr th:first-child {font-weight:bold;}
  table:not(.nostyle) tbody td, table:not(.nostyle) tbody th {display: block; text-align:center;}
  table:not(.nostyle) tbody td, table:not(.nostyle) tbody th:before {
    content: attr(data-th);
    display: block;
    text-align:center;
  }
}