你这个ID为“tb1”的元素是第一个表格吗？能提供更多信息吗？

Css版

csstr:nth-child(2n)>td:nth-child(2n) {
    color: #333;
    background-color: green;
}

tr:nth-child(2n)>td:nth-child(2n+1) {
    color: #666;
    background-color: blue;
}

tr:nth-child(2n+1)>td:nth-child(2n) {
    color: #666;
    background-color: blue;
}

tr:nth-child(2n+1)>td:nth-child(2n+1) {
    color: #333;
    background-color: green;
}

Scss版

scss@mixin style1 {
    color: #333;
    background-color: green;
}

@mixin style2 {
    color: #666;
    background-color: blue;
}

tr {
    &:nth-child(2n) {
        &>td:nth-child(2n) {
            @include style1;            
        }
        &>td:nth-child(2n+1) {
            @include style2;
        }
    }
    &:nth-chlid(2n+1) {
        &>td:nth-child(2n) {
            @include style2;
        }
        &>td:nth-child(2n+1) {
            @include style1;
        }
    }
}