:root {
  --sky: #eaf4fa;
  --navy: #1f3a5f;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  height: 100%;
  overflow: hidden;
  background: var(--sky);
  color: var(--navy);
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  overscroll-behavior: none;
  touch-action: none;
  -webkit-user-select: none;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}

#scene {
  position: fixed;
  inset: 0;
  width: 100%;
  height: 100%;
  display: block;
}

#hint {
  position: fixed;
  top: calc(env(safe-area-inset-top, 0px) + 24px);
  left: 0;
  right: 0;
  margin: 0;
  padding: 0 24px;
  text-align: center;
  font-size: 1rem;
  opacity: 0;
  transition: opacity 0.6s ease;
  pointer-events: none;
}

#hint.show {
  opacity: 1;
}

#overlay {
  position: fixed;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 12px;
  padding: 24px;
  text-align: center;
  background: rgba(234, 244, 250, 0.82);
  transition: opacity 0.4s ease;
}

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

#overlay h1 {
  margin: 0;
  font-size: 2.4rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

#overlay p {
  margin: 0 0 12px;
  max-width: 24ch;
  font-size: 1.05rem;
  line-height: 1.4;
}

#start {
  appearance: none;
  border: 0;
  border-radius: 999px;
  padding: 14px 44px;
  background: var(--navy);
  color: #fff;
  font: inherit;
  font-size: 1.1rem;
  font-weight: 600;
}

#start:active {
  transform: scale(0.97);
}

#start:focus-visible {
  outline: 3px solid #8ecae6;
  outline-offset: 3px;
}

@media (prefers-reduced-motion: reduce) {
  #overlay,
  #hint {
    transition: none;
  }
}