:root {
  --color-light: #ccc;
  --color-dark: #fff;
  --color-background: #222;
}

body {
  background-color: var(--color-background);
}

form {
  font-family: sans-serif;
  position: fixed;
  top: 0;
  left: 0;
  height: 100%;
  width: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
  perspective: 1000px;
  scale: 0.8;
  perspective-origin: 50% 50%;
}

small {
  font-size: 48px;
  display: block;
}

button {
  appearance: none;
  border: unset;
  background: unset;
  font: unset;
  background-image: linear-gradient(to bottom, var(--color-light) 0%, var(--color-dark) 100%);
  width: calc(100% - 30px);
  height: calc(100% - 30px);
  border-radius: 5px;
  transform: scaleX(0.95) scaleY(0.95) rotateX(5deg) translateY(-15px);
  font-size: 100px;
  box-shadow: 10px 10px 30px -10px rgba(0,0,0, 1), inset 0 -10px 3px 15px rgba(0,0,0, 0.5);
}

form.isActive {
  transform: rotate(180deg);
}

form.isActive button {
}