CSS: first child, last child, only child selectors

match element x if:

• tag matches x.
• x has no siblings.

tag is optional. It can be a simple selector (selecting by tag name, id, class etc) or a compound selector (combination of tag name, id, class etc). If empty, it means the universal selector (* any tag).

• test. css :only-child 2026-08-07

match element x if:

• tag matches x.
• x is the first child.

/*
Match span only when it is the 1st child.
Note, this is different from “match the 1st span”.
*/
span:first-child {
 color: red;
}

Match tag only if it is the last child element.