CSS 选择器：ID 或 class 在父级但对子级的规则

Question

I know how to set a CSS-rule für all elements of a type, all elements of a ID and all elements of a type and a ID. But I do not know how to do that if only the parent does have a class or ID.

I want to set the class in the table but I want to define the CSS-rule for the tables element.

Eg Every TH inside a TABLE of class "ABC" should have red textcolor.

<table class="ABC">
<tr>
<th>should be red</th>
<td>should be black</td>
</tr>
</table>

<table>
<tr>
<th>should be black</th>
<td>should be black</td>
</tr>
</table>

How do do this selector?

Answer 1

the descendant selector is simply a space.

table th {} select every th that is a child of table .

table.ABC th select every th that is a child of table with class ABC .

table.ABC th {
  color: red;
}