header {
  text-align: right;
}

body {
  transition: background-color 0.2s ease-in-out, color 0.2s ease-in-out;
  color: #000;
  user-select: none;
}

body[theme="dark"] {
  background: #000;
  color: #fff;
}

h1 {
  color: darkgray;
  font-family: monospace;
  font-size: 8vw;
  text-align: center;
  vertical-align: middle;
}

p {
  color: cadetblue;
  font-family: monospace;
  font-size: 5vw;
  text-align: center;
}

.switch {
  font-size: 17px;
  position: relative;
  display: inline-block;
  width: 3.5em;
  height: 2em;
}

.switch input {
  opacity: 0;
  width: 0;
  height: 0;
}

.slider {
  position: absolute;
  cursor: pointer;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: #f4f4f5b0;
  transition: 0.4s;
  border-radius: 30px;
}

.slider::before {
  position: absolute;
  content: "";
  height: 1.4em;
  width: 1.4em;
  border-radius: 20px;
  left: 0.3em;
  bottom: 0.3em;
  background: gold;
  transition: 0.4s;
}

input:checked + .slider {
  background-color: #303136;
}

input:checked + .slider::before {
  transform: translateX(1.5em);
  background: #303136;
  box-shadow: inset -3px -2px 5px -2px #8983f7, inset -10px -5px 0 0 #a3dafb;
}