* {
  margin: 0;
  padding: 0;
  font-family: 'px';
  font-size: 20px;
}

::-webkit-scrollbar {
  display: none;
}

body {
  display: flex;
  justify-content: center;
}

header {
  position: fixed;
  top: 30px;
  z-index: 1;
  right: 30px;
  display: flex;
  flex-direction: column;
  align-items: flex-end;
}

h1,
button {
  padding: 10px 20px;
  background: white;
  border-radius: 50px;
  border: 1.5px solid black;
  font-size: 20px;
  font-family: 'px';
}

button {
  cursor: pointer;
  margin-bottom: 6px;
  width: 192px;
}

div {
  margin-top: 15px;
  display: flex;
  align-items: center;
}

label {
  margin-right: 30px;
}

input {
  width: 188px;
}

input[type='range'] {
  appearance: none;
  background: none;
}

input[type='range']::-webkit-slider-thumb {
  appearance: none;
  height: 10px;
  width: 10px;
  background: black;
  cursor: pointer;
  border-radius: 50px;
}

input[type='range']::-webkit-slider-runnable-track {
  background: white;
  border-radius: 50px;
  border: solid 2px white;
  outline: 1.5px solid black;
  height: 14px;
}

@property --angle {
  syntax: '<angle>';
  inherits: false;
  initial-value: 0deg;
}

@property --color1 {
  syntax: '<color>';
  inherits: false;
  initial-value: red;
}

@property --color2 {
  syntax: '<color>';
  inherits: false;
  initial-value: cornflowerblue;
}

main {
  opacity: 0.6;
  width: 100vw;
  height: 100vh;
  background: conic-gradient(
    from var(--angle),
    var(--color1),
    var(--color2),
    var(--color1)
  );
  animation: animate 4s linear infinite running;
}

@keyframes animate {
  from {
    --angle: 0deg;
    --color1: red;
    --color2: cornflowerblue;
  }

  33% {
    --color1: springgreen;
    --color2: mediumpurple;
  }

  66% {
    --color1: darkorange;
    --color2: green;
  }

  to {
    --angle: 360deg;
    --color1: red;
    --color2: cornflowerblue;
  }
}