/* Etapa 12 · A grande inversão: a onda que inverte tudo o que atravessa */
.onda{position:fixed;inset:0;z-index:9;pointer-events:none;opacity:0;--r:0px;
 backdrop-filter:invert(1) sepia(.22);-webkit-backdrop-filter:invert(1) sepia(.22);
 -webkit-mask-image:radial-gradient(circle at 50% 50%,transparent calc(var(--r) - 15vmax),rgba(0,0,0,.25) calc(var(--r) - 9vmax),rgba(0,0,0,.9) calc(var(--r) - 2vmax),#000 calc(var(--r) - 2px),transparent var(--r));
 mask-image:radial-gradient(circle at 50% 50%,transparent calc(var(--r) - 15vmax),rgba(0,0,0,.25) calc(var(--r) - 9vmax),rgba(0,0,0,.9) calc(var(--r) - 2vmax),#000 calc(var(--r) - 2px),transparent var(--r))}
.onda.on{opacity:1}
.onda::after{content:"";position:absolute;left:50%;top:50%;width:calc(var(--r) * 2);height:calc(var(--r) * 2);transform:translate(-50%,-50%);border-radius:50%;box-shadow:0 0 0 1px rgba(255,236,214,.5),0 0 40px 6px rgba(255,214,170,.25)}
@media (prefers-reduced-motion:reduce){.onda{display:none}}