/* L14-A R3: a recessed, neutral optical membrane behind the supplied shell.
   No masks, backdrop filters, blending or animation on this material. */
.agent-card-shell[data-premium-shell]::before {
  content: "";
  position: absolute;
  inset: 4px;
  z-index: 0;
  pointer-events: none;
  border: 0;
  border-radius: var(--card-corner-radius);
  background:
    radial-gradient(ellipse 78% 30% at 32% 0%, rgba(247,253,255,.10), transparent 90%),
    radial-gradient(ellipse 30% 27% at 79% 49%, rgba(235,248,255,.028), transparent 100%),
    radial-gradient(ellipse 9% 33% at 0% 24%, rgba(232,248,255,.025), transparent 100%),
    radial-gradient(ellipse 8% 24% at 100% 77%, rgba(219,237,253,.02), transparent 100%),
    radial-gradient(ellipse 88% 24% at 43% 104%, rgba(164,213,248,.05), transparent 100%),
    /* Shared vertical optical density, independent of shell mirroring.
       Widely spaced alpha stops keep the progression free of a visible band. */
    linear-gradient(180deg,
      rgba(39,70,101,.018) 0%,
      rgba(39,70,101,.022) 20%,
      rgba(39,70,101,.032) 40%,
      rgba(39,70,101,.052) 60%,
      rgba(39,70,101,.078) 80%,
      rgba(39,70,101,.105) 100%);
  /* A soft contact edge and opposing reflection imply depth without a border.
     These shadows belong only to the inset face, never to the PNG shell. */
  box-shadow:
    inset 0 3px 7px -3px rgba(27,57,84,.24),
    inset 2px 0 6px -3px rgba(27,57,84,.14),
    inset 0 0 2px rgba(43,76,102,.10),
    inset 0 -2px 4px -2px rgba(241,252,255,.34);
}
/* The central PNG's clear aperture is shorter than its layout container. */
.agent-card-shell[data-premium-shell][data-side="center"]::before {
  inset: 23px 6px;
}
/* Retain the existing icon container and all its geometry, but remove its
   former full-face material so the dedicated membrane is the only surface. */
.agent-card-shell[data-premium-shell] .agent-card-plane--front {
  background: none;
  backdrop-filter: none;
  -webkit-backdrop-filter: none;
  box-shadow: none;
}