/* Fondo de placa de circuito (portada y setup). La placa es una imagen (assets/circuit.svg, se pinta una sola vez);
   encima, unos pocos pulsos dorados recorren pistas de esa misma placa (<use href="assets/circuit.svg#pN">). */
.cb{position:absolute;inset:0;overflow:hidden;pointer-events:none}
.cb img,.cb svg{position:absolute;inset:0;width:100%;height:100%;object-fit:cover}
.cb img{opacity:.6}
.cb-pulse{fill:none;stroke:var(--gold-hi);stroke-width:2.5;stroke-linecap:round;stroke-dasharray:3 97;stroke-dashoffset:100;opacity:.85;animation:cb-run 8s linear infinite}
.cb-pulse:nth-of-type(2n){animation-duration:11s;animation-delay:-4s}
.cb-pulse:nth-of-type(3n){animation-duration:13s;animation-delay:-7s}
@keyframes cb-run{to{stroke-dashoffset:0}}
@media (prefers-reduced-motion:reduce){.cb-pulse{display:none}}