style.css

@import url('https://pro.fontawesome.com/releases/v6.0.0-beta1/css/all.css');

button.neumorphic {
  container-type: inline-size;
  aspect-ratio: 1/1;
  border: 0.5rem solid transparent;
  border-radius: 1rem;
  color: hsl(0 0% 10%);
  background: none;
  
  display: grid;
  place-content: center;
  gap: 1rem;
  
  --shadow: 
    -.5rem -.5rem 1rem hsl(0 0% 100% / .75),
    .5rem .5rem 1rem hsl(0 0% 50% / .5);
  box-shadow: var(--shadow);
  outline: none;  
  transition: all 0.1s;
  
  &:hover, &:focus-visible {
    color: hsl(10 80% 50%);
    scale: 1.1
  }
  &:active, &.active{
    box-shadow:
      var(--shadow),
      inset .5rem .5rem 1rem hsl(0 0% 50% / .5),
      inset -.5rem -.5rem 1rem hsl(0 0% 100% / .75);
    color: hsl(10 80% 50%);
    > i { font-size: 28cqi};
    > span { font-size: 13cqi};
  }

  >i {
    font-size: 31cqi;
  }
  > span {
    font-family: system-ui, sans-serif;
    font-size: 16cqi;
  }
}

body {
  background-color: #283593;
  padding: 2rem;
}
h1 {
  text-align: center;
  color: hsl(0 0% 10%);
  font-family: system-ui, sans-serif;
  font-size: 3rem;
}
.buttons {
  display: grid;
  width: min(75rem, 100%);
  margin-inline: auto;
  grid-template-columns: repeat(auto-fit, minmax(min(8rem, 100%), 1fr));
  gap: 2rem;
}