Can a recursive variable be expressed in css?

For the html:

<body>
<div>
  <div>
    <div>
      ...
    </div>
  </div>
</div>
</body>

Are there any ways to create a recursive variable that uses its parent's value:

body > div {
    --x: 1;
}

div {
    --x: calc(var(--x) + 1);
}

The above is not valid because css variables cannot have dependency cycles. Another invalid example:

body > div {
    --is-even: 0;
    --is-odd: 1;
}

div {
    --is-even: var(--is-odd);
    --is-odd: var(--is-even);
}

Are there any indirect ways to express such recursive variables in css?

Solution

You can use two CSS variables to simulate the recursive behavior and avoid cycle dependency.

Here is an example:

body {
  --x: 10;
}
.y {
  --y: calc(var(--x) + 1);
}
.x{
  --x: calc(var(--y) + 1);
}
.result {
  border-right:calc(1px * var(--y)) solid red;
  border-left:calc(1px * var(--x)) solid green;
  height:50px;
}

<body>
  <div class="y">
    <div class="x">
      <div class="y">
        <div class="x">
          <div class="y">
            <div class="x">
              <div class="y result">

              </div>
            </div>
          </div>
        </div>
      </div>
    </div>
  </div>
</body>

If you inspect the element you will find for the last element that border-right is equal to 17px (10 + 7) and border-left is equal to 16px (10 + 6)

This idea fits nicely in elements with a 2 level structure, like lists:

body {
  --x: 30;
}

ul { 
    font-size: calc(var(--x) * 1px);
    --y: calc(var(--x) - 8);
}

li {
  --x: calc(var(--y));
}

  <ul>level A
    <li>item 1
    </li>
    <li>item 2
      <ul>level B
        <li>item 2.1
          <ul>level C
            <li>item 2.1.1
            </li>
            <li>item 2.1.2
            </li>
          </ul>
        </li>
        <li>item 2.2
        </li>
      </ul>
    </li>
  </ul>