body {
  margin: 0;
  overflow: hidden;
}

/* 仅作背景音的 MP4：不占画面、不参与点击 */
.bgm-video {
  position: fixed;
  left: 0;
  top: 0;
  width: 1px;
  height: 1px;
  opacity: 0;
  pointer-events: none;
  z-index: 0;
}

.site-hero {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 10;
  padding: clamp(1rem, 3.5vw, 1.75rem) 1.25rem 0.75rem;
  text-align: center;
  pointer-events: none;
}

.site-hero__title {
  margin: 0;
  font-family: "Outfit", system-ui, sans-serif;
  font-weight: 800;
  font-size: clamp(1.15rem, 3.2vw, 2rem);
  letter-spacing: 0.04em;
  line-height: 1.25;
  color: #f4feff;
  text-shadow:
    0 0 1px rgba(0, 24, 32, 0.9),
    0 2px 18px rgba(0, 40, 56, 0.65),
    0 0 42px rgba(0, 120, 160, 0.35);
}

.site-hero__subtitle {
  margin: 0.45rem 0 0;
  font-family: "Outfit", system-ui, sans-serif;
  font-weight: 500;
  font-size: clamp(0.8rem, 2vw, 1rem);
  letter-spacing: 0.22em;
  color: rgba(220, 248, 255, 0.88);
  text-shadow: 0 1px 12px rgba(0, 20, 30, 0.55);
}

#bgm-toggle {
  position: fixed;
  right: clamp(0.75rem, 2.5vw, 1.25rem);
  bottom: clamp(0.75rem, 2.5vw, 1.25rem);
  z-index: 11;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.65rem;
  height: 2.65rem;
  padding: 0;
  color: #e8fbff;
  background: rgba(2, 24, 32, 0.55);
  border: 1px solid rgba(120, 220, 255, 0.35);
  border-radius: 999px;
  cursor: pointer;
  backdrop-filter: blur(6px);
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.25);
}

#bgm-toggle svg {
  display: block;
  pointer-events: none;
}

#bgm-toggle:hover {
  background: rgba(8, 50, 60, 0.72);
  border-color: rgba(160, 240, 255, 0.5);
}

#bgm-toggle:focus-visible {
  outline: 2px solid #7ee8ea;
  outline-offset: 2px;
}