/* 背景を斜めに走る光（全ページ共通） */
.bg-sweep{
  position:fixed;inset:0;z-index:0;pointer-events:none;overflow:hidden;
}
.stage > .bg-sweep{position:absolute}
.bg-sweep i{
  position:absolute;top:-35%;left:0;
  width:22vmin;height:170%;
  background:linear-gradient(90deg,
    transparent 0%,
    rgba(79,216,255,0) 28%,
    rgba(79,216,255,.20) 48%,
    rgba(122,108,245,.16) 56%,
    rgba(255,77,141,.10) 68%,
    transparent 100%);
  filter:blur(14px);
  mix-blend-mode:screen;
  animation:bg-sweep 8.8s ease-in-out infinite;
  transform:translateX(-50vw) rotate(14deg);
}
.bg-sweep i:nth-child(2){
  width:9vmin;
  opacity:.7;
  filter:blur(8px);
  animation-duration:12.5s;
  animation-delay:3.6s;
  background:linear-gradient(90deg,
    transparent,
    rgba(79,216,255,.32),
    transparent);
}
@keyframes bg-sweep{
  0%{transform:translateX(-55vw) rotate(14deg);opacity:0}
  12%{opacity:1}
  78%{opacity:.75}
  100%{transform:translateX(135vw) rotate(14deg);opacity:0}
}
@media (prefers-reduced-motion:reduce){
  .bg-sweep{display:none}
}