<!DOCTYPE html>
<style>
  #target {
    transition-timing-function: linear(calc(15 / 0), 10 10%);
    transition-duration: 10s;
  }
</style>
<script>
  window.addEventListener('load', () => {
    target.style.paddingBlock = "10px 10px";
  })
</script>
<slot id="target"></slot>
