* { box-sizing: border-box; }
body {
  margin: 0;
  background: #f8f8f8;
  color: #111;
  font-family: Arial, Helvetica, sans-serif;
}
main {
  min-height: 100vh;
  min-height: 100svh;
  display: flex;
  flex-direction: column;
  text-align: center;
}
.screens {
  display: flex;
  flex: 1;
  width: 100%;
  overflow-x: auto;
  overscroll-behavior-x: contain;
  scroll-snap-type: x mandatory;
  scrollbar-width: none;
}
.screens::-webkit-scrollbar { display: none; }
.panel {
  flex: 0 0 100%;
  min-width: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 40px 24px 0;
  scroll-snap-align: start;
  scroll-snap-stop: always;
}
h1 {
  margin: 0;
  font-size: clamp(36px, 8vw, 56px);
  font-weight: 700;
  letter-spacing: -2px;
}
.intro { margin: 14px 0 42px; color: #666; font-size: 16px; line-height: 1.5; }
.ball {
  flex-shrink: 0;
  width: min(400px, 84vw, 100%);
  aspect-ratio: 1;
  padding: 0;
  border: 0;
  border-radius: 50%;
  background: #111;
  color: #111;
  display: grid;
  place-items: center;
  cursor: pointer;
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
  box-shadow: 0 18px 30px -22px #555;
  transition: transform 180ms ease, box-shadow 180ms ease;
}
@media (hover: hover) {
  .ball:hover { transform: translateY(-4px); box-shadow: 0 24px 34px -22px #555; }
}
.ball:active { transform: scale(.97); }
.ball:focus-visible { outline: 2px solid #111; outline-offset: 8px; }
.window {
  display: grid;
  place-items: center;
  width: 52%;
  aspect-ratio: 1;
  padding: 17px;
  border-radius: 50%;
  background: #fff;
}
.answer { font-size: clamp(15px, 4vw, 23px); font-weight: 700; line-height: 1.3; }
.answer.initial { font-size: clamp(72px, 26vw, 130px); line-height: 1; }
.hint { margin: 36px 0 0; min-height: 84px; font-size: 11px; line-height: 1.5; letter-spacing: 2px; text-transform: uppercase; color: #666; }
.no-mark { font-size: clamp(44px, 15vw, 76px); font-weight: 700; letter-spacing: -3px; }
.no-reason { width: min(440px, 100%); min-height: 84px; margin: 36px 0 0; font-size: 17px; line-height: 1.5; overflow-wrap: anywhere; }
.navigation { display: flex; justify-content: center; align-items: center; gap: 2px; }
.navigation button { border: 0; background: transparent; color: #111; cursor: pointer; width: 44px; height: 44px; padding: 0; touch-action: manipulation; }
.navigation button:focus-visible { outline: 2px solid #111; outline-offset: 2px; border-radius: 4px; }
.nav-arrow { font-size: 24px; }
.navigation button:disabled { color: #bbb; cursor: default; }
.dot::after { content: ''; display: block; width: 7px; height: 7px; border: 1px solid #888; border-radius: 50%; margin: auto; }
.dot[aria-current="true"]::after { background: #111; border-color: #111; }
.swipe-hint { margin: 4px 0 24px; color: #666; font-size: 11px; letter-spacing: 1px; }
.ball.shaking { animation: shake 450ms ease-in-out; }
@keyframes shake {
  0%, 100% { transform: rotate(0); }
  20%, 60% { transform: rotate(-9deg); }
  40%, 80% { transform: rotate(9deg); }
}
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip-path: inset(50%); white-space: nowrap; border: 0; }
@media (prefers-reduced-motion: reduce) {
  .ball { transition: none; }
  .ball.shaking { animation: none; }
}