/* ===== SHELL GAME ===== */
.sg-stage {
  width: 100%;
  max-width: 400px;
  height: 300px;
  background: rgba(0, 0, 0, 0.2);
  border-radius: var(--radius);
  position: relative;
  overflow: hidden;
  margin: 10px auto;
  box-shadow: inset 0 4px 10px rgba(0,0,0,0.5);
}

.sg-message {
  text-align: center;
  font-size: 1.1rem;
  font-weight: 700;
  margin: 10px 0;
  color: #fff;
  min-height: 1.5em;
}

.sg-cup {
  width: 60px;
  height: 60px;
  position: absolute;
  /* glass style for cup */
  background: linear-gradient(135deg, rgba(255,255,255,0.1), rgba(255,255,255,0.02));
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid rgba(255,255,255,0.2);
  border-radius: 12px;
  box-shadow: 0 4px 15px rgba(0,0,0,0.4);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2rem;
  cursor: pointer;
  /* Smooth transition for movement */
  transition: top 0.4s ease-in-out, left 0.4s ease-in-out, transform 0.2s, background 0.3s;
  user-select: none;
}

/* When waiting for tap, elevate slightly on hover */
.sg-cup.tap-ready:hover {
  transform: translateY(-5px);
  border-color: var(--primary);
  box-shadow: 0 8px 25px rgba(139, 92, 246, 0.5);
}

/* Revealed state (star or empty) */
.sg-cup.revealed {
  background: rgba(255,255,255,0.2);
  border-color: rgba(255,255,255,0.5);
  cursor: default;
}
.sg-cup.revealed:hover {
  transform: none;
  box-shadow: 0 4px 15px rgba(0,0,0,0.4);
}

.sg-star {
  display: none;
}
.sg-cup.revealed .sg-star {
  display: block;
  animation: popStar 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

@keyframes popStar {
  0%   { transform: scale(0.5); opacity: 0; }
  100% { transform: scale(1); opacity: 1; }
}

.sg-empty {
  display: none;
  color: var(--muted);
  font-size: 1.5rem;
}
.sg-cup.revealed .sg-empty {
  display: block;
}

/* 鬼ボタン */
.diff-btn.oni-btn {
  background: linear-gradient(135deg, #7f1d1d, #dc2626);
  color: #fff;
  border-color: #ef4444;
  font-weight: 900;
}
.diff-btn.oni-btn.selected,
.diff-btn.oni-btn:hover {
  background: linear-gradient(135deg, #dc2626, #f97316);
  box-shadow: 0 0 12px rgba(239, 68, 68, 0.7);
  border-color: #f97316;
}