calc-size

calc-size is a new [[css]] function that allows you to calculate using keywords.

.height-example {
  block-size: calc-size(auto, size + 24px)
}

.width-example {
  inline-size: calc-size(max-content, size * .5);
}

The first value is the keyword you want to do the calculation on, and the second value uses said keyword (mapped to size) and allows you to calculate with it.