DOM's mindset defines CSS

In fact, before reading this document, I thought this way too.
"Document object path" is familiar to everyone
I applied this way of thinking to css definition.
For example:
There is such a table
<Table id = "table">
<Tbody>
<Tr class = "tr1">
<Td class = "td1"> 1 </td>
<Td> 2 </td>
<Td> 3 </td>
</Tr>
<Tr>
<Td> 1 </td>
<Td> 2 </td>
<Td> 3 </td>
</Tr>
</Table>
I want to control the tr style in the table
<Style>
# Table tbody tr {
.......................................
}
</Style>
Controls the td style in the table
<Style>
# Table tbody tr td {
.......................................
}
</Style>
Controls the td in a tr.
<Style>
# Table tbody tr. tr1 td {
.......................................
}
</Style>
Controls a td in a tr.
<Style>
# Table tbody tr. tr1 td. td1 {
.......................................
}
</Style>
Is there a level-1 experience?
I personally feel that writing is very standard.
Do not blame me if I think that my thinking is not accurate.