/* ══════════════════════════════════════════
   MARCA DE DIGITAL CORE · la esfera con «IA»
   Misma identidad que la intro (#intro-overlay: anillos + núcleo con «IA»),
   en tamaño logo para la tarjeta de login y la barra superior del Hub. Los
   anillos giran despacio y reutilizan los @keyframes introSpin/introSpinRev
   de layout/overlays.css; bajo «reducir movimiento» quedan quietos. Es una
   superficie de marca: único sitio fuera de la intro con el degradado de marca
   (One-Gradient Rule, DESIGN.md).
══════════════════════════════════════════ */

.brand-sphere {
  position: relative;
  width: 40px;
  height: 40px;
  flex-shrink: 0;
}

.brand-sphere-ring {
  position: absolute;
  border-radius: 50%;
  border: 1.5px solid transparent;
  transform-origin: 50% 50%;
  transform: translateZ(0);
  will-change: transform;
}

.brand-sphere-ring-1 {
  inset: 0;
  border-top-color: var(--logo-gradient-start);
  border-right-color: color-mix(in srgb, var(--accent) 35%, transparent);
  animation: introSpin 2.6s linear infinite;
}

.brand-sphere-ring-2 {
  inset: 4px;
  border-bottom-color: var(--logo-gradient-end);
  border-left-color: color-mix(in srgb, var(--logo-gradient-end) 35%, transparent);
  animation: introSpinRev 2s linear infinite;
}

.brand-sphere-core {
  position: absolute;
  inset: 8px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--logo-gradient-start) 0%, var(--logo-gradient-end) 100%);
  box-shadow: 0 0 12px color-mix(in srgb, var(--accent) 35%, transparent), inset 0 0 6px color-mix(in srgb, var(--surface-white) 22%, transparent);
  color: var(--on-accent);
  font-family: var(--font-display);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.3px;
  line-height: 1;
  user-select: none;
  will-change: transform;
  animation: introCorePulse 1.8s ease-in-out infinite;
}

/* Variante compacta (barra superior del Hub). */
.brand-sphere-sm { width: 32px; height: 32px; }
.brand-sphere-sm .brand-sphere-ring-2 { inset: 3px; }
.brand-sphere-sm .brand-sphere-core { inset: 6px; font-size: 8.5px; }

/* Reducir movimiento: igual que la intro, no se congela; solo va más despacio. */
@media (prefers-reduced-motion: reduce) {
  .brand-sphere-ring-1 { animation-duration: 3.8s; }
  .brand-sphere-ring-2 { animation-duration: 3.2s; }
  .brand-sphere-core { animation: none; }
}