id="myCE">I should be green</custom-state>
    <p id="mySibling">I should be blue</p>
    <p id="myHas">I should be blue</p>
    <style>
      custom-state {
        color: #f00;
      }
      custom-state + p {
        color: #f00;
      }
      custom-state:state(--green) {
        color: #0f0;
      }
      custom-state:--green {
        color: #0f0;
      }
      body:has(custom-state:state(--green)) p {
        color: #0ff;
      }
      custom-state:state(--green) + p[id] {
        color: #00f;
      