html, body {
  margin: 0;
  padding: 0;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

main {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  height: 100vh;
  position: relative;
}

.overlay, .end, .start {
  position: absolute;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  z-index: 10;
  background-color: rgba(255, 255, 255, 0.75);
  transition: opacity ease-in-out 0.75s;
  display: flex;
  justify-content: center;
  align-items: center;
}

.start>a {
  text-decoration: none;
}

.overlay.overlay--inactive {
  opacity: 0;
  pointer-events: none;
}

.overlay.overlay--active {
  opacity: 1;
}

.overlay.overlay--success, .end.end--won {
  background-color: rgba(200, 255, 200, 0.75);
}

.overlay.overlay--failure, .end.end--lost {
  background-color: rgba(255, 200, 200, 0.75);
}

.overlay-content, .end, .start {
  font-size: 10rem;
}

section.score {
  position: absolute;
  top: 0.5rem;
  z-index: 5;
}

section.task > p {
  display: flex;
  justify-content: center;
}

section.task > p > span {
  display: block;
  font-size: 7rem;
  width: 10.0rem;
  text-align: center;
}

section.options {
  margin-top: 4rem;
}

section.options > ul {
  display: flex;
  justify-content: center;
  margin: 0;
  padding: 0;
}

section.options > ul {
  display: flex;
  justify-content: center;
  margin: 0;
  padding: 0;
}

section.options > ul > li {
  display: block;
  font-size: 3.5rem;
  width: 3.75rem;
  text-align: center;
}

section.options > ul > li:not(:first-child) {
  margin-left: 2rem;
}

section.countdown {
  position: absolute;
  bottom: 0.5rem;
  z-index: 5;
}