:root {
  
  --val: 15rem; /* use any length unit (px, em, ex, ch, rem, ...)*/
  --unitless-val: tan(atan2(var(--val), 1rem)); /** Fundamentally, tan(atan2()) is just a scalar between two dimensions. */
  
  --val2: 34%; /* use any length unit (px, em, ex, ch, rem, ...)*/
  --unitless-val2: tan(atan2(var(--val2), 1%)); /** Fundamentally, tan(atan2()) is just a scalar between two dimensions. */
  
  
  --val3: 34ch; /* use any length unit (px, em, ex, ch, rem, ...)*/
  --unitless-val3: tan(atan2(var(--val3), 1ch)); /** Fundamentally, tan(atan2()) is just a scalar between two dimensions. */

  --val4: 12vw;
   --unitless-val4: calc(tan(atan2(var(--val4), 1vw))); /* calc() wrapper required for Safari, bug:
  // https://bugs.webkit.org/show_bug.cgi?id=263000
  */
  
}

/* show the unitless value */
body:before {
  
  content: 'from "rem": ' counter(c) ', from "%": ' counter(d) ', from "ch": ' counter(e) ', from "vw": ' counter(f);
  counter-reset: c var(--unitless-val) d var(--unitless-val2) e var(--unitless-val3) f var(--unitless-val4);
  
  font-size: 45px;
  font-weight: bold;
  font-family: system-ui,sans-serif;
}