/* ズームする背景画像 */
@keyframes gentle-wave-zoom {
  0% {
    transform: scale(1);
  }
  100% {
    transform: scale(1.1);
  }
}

.hero-background {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-size: cover;
  background-position: center;
  background-image: url('../images/img_main/main_img_mobile.webp');
  animation: gentle-wave-zoom 25s ease-in-out infinite alternate;
  z-index: 0;
}

@media (min-width: 880px) {
    .hero-background {
        background-image: url('../images/img_main/main_img_desktop.webp');
    }
}

/* パーティクルアニメーション */
.particle-container {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  overflow: hidden;
  z-index: 1;
}

.particle {
  position: absolute;
  bottom: -20px;
  border: 1px solid rgba(255, 254, 225, 0.8);
  border-radius: 50%;
  animation: rise 10s infinite ease-in;
}

@keyframes rise {
  0% {
    transform: translateY(0) translateX(0);
    opacity: 0;
  }
  40% {
    opacity: 0.7;
  }
  100% {
    transform: translateY(-100vh) translateX(-50px);
    opacity: 0;
  }
}

.particle:nth-child(1) { width: 10px; height: 10px; left: 15%; animation-duration: 12s; animation-delay: -1s; }
.particle:nth-child(2) { width: 15px; height: 15px; left: 30%; animation-duration: 15s; animation-delay: -2s; }
.particle:nth-child(3) { width: 8px; height: 8px; left: 50%; animation-duration: 18s; animation-delay: -4s; }
.particle:nth-child(4) { width: 12px; height: 12px; left: 75%; animation-duration: 10s; animation-delay: -1.5s; }
.particle:nth-child(5) { width: 18px; height: 18px; left: 85%; animation-duration: 16s; animation-delay: -5.5s; }
.particle:nth-child(6) { width: 7px; height: 7px; left: 5%; animation-duration: 20s; animation-delay: -3s; }
.particle:nth-child(7) { width: 14px; height: 14px; left: 40%; animation-duration: 13s; animation-delay: -5s; }
.particle:nth-child(8) { width: 10px; height: 10px; left: 60%; animation-duration: 17s; animation-delay: -8s; }
.particle:nth-child(9) { width: 16px; height: 16px; left: 90%; animation-duration: 11s; animation-delay: -0.5s; }
.particle:nth-child(10) { width: 9px; height: 9px; left: 25%; animation-duration: 14s; animation-delay: -7s; }
.particle:nth-child(11) { width: 11px; height: 11px; left: 20%; animation-duration: 19s; animation-delay: -5s; }
.particle:nth-child(12) { width: 13px; height: 13px; left: 35%; animation-duration: 12.5s; animation-delay: -5s; }
.particle:nth-child(13) { width: 6px; height: 6px; left: 55%; animation-duration: 22s; animation-delay: -3s; }
.particle:nth-child(14) { width: 17px; height: 17px; left: 80%; animation-duration: 14.5s; animation-delay: -5s; }
.particle:nth-child(15) { width: 9px; height: 9px; left: 63%; animation-duration: 18.5s; animation-delay: -2.5s; }
.particle:nth-child(16) { width: 12px; height: 12px; left: 10%; animation-duration: 16.5s; animation-delay: -5s; }
.particle:nth-child(17) { width: 14px; height: 14px; left: 45%; animation-duration: 11.5s; animation-delay: -4s; }
.particle:nth-child(18) { width: 8px; height: 8px; left: 65%; animation-duration: 19.5s; animation-delay: -5s; }
.particle:nth-child(19) { width: 15px; height: 15px; left: 70%; animation-duration: 13.5s; animation-delay: -6s; }
.particle:nth-child(20) { width: 10px; height: 10px; left: 0%; animation-duration: 21s; animation-delay: -5s; }