@import url('https://fonts.googleapis.com/css2?family=Bitcount+Prop+Single:wght@100..900&display=swap');

body {
  background: #eee;
  display: flex;
  min-height: 100vh;
  padding: 0;
  align-items: center;
  justify-content: center;
}
@keyframes rainbow {
  0% {
    --angle: 0deg;
  }
  100% {
    --angle: 360deg;
  }
}
@property --angle {
  syntax: '<angle>';
  inherits: false;
  initial-value: 0deg;
}
button {
  --angle: 0deg;
  outline: 0;
  border: none;
  padding: 0.75rem;
  cursor: pointer;
  position: relative;
  background-color: transparent;

  &::before {
    border-radius: 2rem;
    background: conic-gradient(
      from var(--angle),
      rgba(255, 0, 0, 0.5) 0%,
      rgba(255, 154, 0, 0.5) 10%,
      rgba(208, 222, 33, 0.5) 20%,
      rgba(79, 220, 74, 0.5) 30%,
      rgba(63, 218, 216, 0.5) 40%,
      rgba(47, 201, 226, 0.5) 50%,
      rgba(28, 127, 238, 0.5) 60%,
      rgba(95, 21, 242, 0.5) 70%,
      rgba(186, 12, 248, 0.5) 80%,
      rgba(251, 7, 217, 0.5) 90%,
      rgba(255, 0, 0, 0.5) 100%
    );
    box-shadow: inset 0 0 50px #eee;
    width: 100%;
    height: 100%;
    content: '';
    display: block;
    position: absolute;
    top: 0;
    left: 0;
    filter: blur(0.8rem);
    z-index: -2;
    opacity: 0.7;
    animation: rainbow 3s linear infinite;
  }
  .glass {
    position: relative;
    padding: 0.75rem;
    border-radius: 1.5em;
    background-color: rgba(255, 255, 255, 0.5);
    box-shadow: 0 0 5px rgba(255, 255, 255, 0.4), 0 2px 10px rgba(0, 0, 0, 0.05),
      inset 0 0 10px rgba(255, 255, 255, 0.6);

    &::before {
      content: '';
      width: calc(100% + 4px);
      height: calc(100% + 4px);
      position: absolute;
      background: linear-gradient(to bottom, white, black, white);
      opacity: 0.2;
      top: -2px;
      left: -2px;
      z-index: -1;
      border-radius: 1.5em;
    }
  }
  .outer {
    transition: transform 0.3s ease-in-out;
    padding: 1rem;
    border-radius: 1rem;
    background: linear-gradient(to top, rgba(34, 34, 34, 1) 0%, rgba(55, 55, 55, 1) 100%);
    box-shadow: 0 5px 5px rgba(0, 0, 0, 0.4);
    &:hover {
      transform: scale(1.03);
    }
  }
  .inner {
    font-family: 'Bitcount Prop Single', system-ui;
    font-optical-sizing: auto;
    font-weight: <weight>;
    font-style: normal;
    font-variation-settings: 'slnt' 0, 'CRSV' 0.5, 'ELSH' 0, 'ELXP' 0;
    font-size: 2rem;
    font-weight: 400;
    padding: 0.75rem 1.5rem;
    color: #eee;
    border-radius: 2rem;
    background: linear-gradient(to bottom, rgba(34, 34, 34, 1) 0%, rgba(55, 55, 55, 1) 100%);
    &:active {
      background: linear-gradient(to top, rgba(34, 34, 34, 1) 0%, rgba(55, 55, 55, 1) 100%);
    }
  }
}