/* REGISTER VAR TO BE ANIMATABLE*/
@property --percentage {
  initial-value: 0;
  inherits: false;
  syntax: '<number>';
}

/* animating the custom prop*/
@keyframes updatePerc {
  to {
    --percentage: 100;
  }
}

:root {
  animation: updatePerc linear; 
  animation-timeline: scroll();
  
  /* create some custom props to derive different effects*/
 --primary-color: hsl(calc(var(--percentage, 0) * 3.6), 45%, 56%);
 --angle: calc(var(--percentage, 0) * 3.6deg);
 --txt: calc(var(--percentage));
}

/* Drawing the arc */
.progress:after {
  background: conic-gradient(
    var(--primary-color) var(--angle),
    transparent var(--angle)
  ); 
}

/* Number as text */
.progress__txt:after {
  counter-reset: myCounter var(--txt);
  content: counter(myCounter) "%";
  display: block;
}



  /*COSMETIC*/
.progress {
  --borderWidth: 10px;
	--size: 8rem;
  border-radius:100%;  
	width: var(--size);
	height: var(--size);
	margin: 60px auto;
	border: 1px solid white;
	position: fixed;
	display: flex;
	justify-content: center;
	align-items: center;
  top: 2rem;
  right: 2rem;
  z-index: 2;
  font-size: 2em;
}
.progress:before {
  border-radius: 100%;
	content: '';
	width: calc(var(--size) - var(--borderWidth) );
	height: calc(var(--size) - var(--borderWidth));
	position: absolute;
	background: #222;
	z-index: 1;
}
.progress:after {
  border-radius: 100%;
	content: '';
	position: absolute;
	top: calc(var(--borderWidth)  / -2);
	left: calc(var(--borderWidth) / -2);
	width: calc(var(--size) + var(--borderWidth));
	height: calc(var(--size) + var(--borderWidth))
}

.progress__txt {
  z-index: 2;
}

/* GENERAL DOCUMENT COSMETIC */
main{
  width: min(90%, 80ch);
  margin-inline: auto;

}
img {
  width: 100%;
}
body{
  margin: 0;
  padding: 0;
  padding-top: 2rem;
  font-family: sans-serif;
  background: #222;
  color: #bbb;
}

h1 {
  width: 100%;   
  position:sticky;
  top: 0;
  color:  var(--primary-color);
  background: #222;
  font-size: 5em;
  line-height: 0.9;
  z-index: 1;
  padding-block: 2rem;
  margin-inline: -2em;
  padding-inline: 2em;
}
p{
  line-height: 1.75;
}