csscss-selectors

Can CSS detect the number of children an element has?

I'm probably answering my own question, but I'm extremely curious.

I know that CSS can select individual children of a parent, but is there support to style the children of a container, if its parent has a certain amount of children.

for example

container:children(8) .child {
  //style the children this way if there are 8 children
}

I know it sounds weird, but my manager asked me to check it out, haven't found anything on my own so I decided to turn to SO before ending the search.

Solution

  • Clarification:

    Because of a previous phrasing in the original question, a few SO citizens have raised concerns that this answer could be misleading. Note that, in CSS3, styles cannot be applied to a parent node based on the number of children it has. However, styles can be applied to the children nodes based on the number of siblings they have.

    Original answer:

    Incredibly, this is now possible purely in CSS3.

    /* one item */
li:first-child:nth-last-child(1) {
/* -or- li:only-child { */
    width: 100%;
}

/* two items */
li:first-child:nth-last-child(2),
li:first-child:nth-last-child(2) ~ li {
    width: 50%;
}

/* three items */
li:first-child:nth-last-child(3),
li:first-child:nth-last-child(3) ~ li {
    width: 33.3333%;
}

/* four items */
li:first-child:nth-last-child(4),
li:first-child:nth-last-child(4) ~ li {
    width: 25%;
}

    The trick is to select the first child when it's also the nth-from-the-last child. This effectively selects based on the number of siblings.

    Credit for this technique goes to André Luís (discovered) & Lea Verou (refined).

    Don't you just love CSS3? 😄

    CodePen Example:

    Sources: