:root {
  color-scheme: light dark;
}

#popup {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 2;
}

#popup .auth-area {
  margin: 0.5em;
  padding: 1em;
}
#popup .auth-area .center {
  background-color: transparent;
  text-align: center;
  font-size: 1.5em;
  width: 8em;
  border: 1px solid #888;
}
#popup .auth-area .center.btn {
  margin-top: 0.3em;
  border-radius: 1em;
  width: 5em;
}
#popup button:enabled {
  cursor: pointer;
}
#popup button:disabled {
  color: #888;
  opacity: 0.7;
}

#popup {
  display: grid;
  place-content: center;
  gap: 0.5em;

  text-align: center;
  line-height: 1.42;
  background-color: #444;
  opacity: 0.9;
}

#popup * {
  box-sizing: border-box;
  color: #eee;
}

#popup .grid-area {
  width: 38em;
  height: 30em;
  border-radius: 2em;

  display: grid;
  place-content: center;
  text-align: center;

  font-size: 1.5vmin;
}

#popup .white-area {
  display: inline-block;
}

#popup .rainbow {
  width: 20em;
  height: 15em;
  border-radius: 1em;
  padding: 2em;
  margin: auto;

  display: grid;
  place-content: center;
  text-align: center;

  font-size: 1.5em;

  --border-size: 0.2em;
  border: var(--border-size) dotted transparent;
  background-image: linear-gradient(
      to right,
      rgb(28 28 28 / var(--opacity)),
      rgb(58 58 58 / var(--opacity))
    ),
    conic-gradient(
      from var(--angle),
      #d53e33 0deg 90deg,
      #fbb300 90deg 180deg,
      #377af5 180deg 270deg,
      #399953 270deg 360deg
    );
  background-origin: border-box;
  background-clip: padding-box, border-box;
}

@supports (background: paint(houdini)) {
  @property --opacity {
    syntax: "<number>";
    initial-value: 0.5;
    inherits: false;
  }

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

  @keyframes opacityChange {
    to {
      --opacity: 1;
    }
  }

  @keyframes rotate {
    to {
      --angle: 360deg;
    }
  }

  .rainbow {
    animation: rotate 4s linear infinite, opacityChange 3s infinite alternate;
  }
}