/* Shared AIR nine-slice surface. Keep the bitmap on its own paint layer so
   layout padding and scroll children do not distort the source corner caps. */
.air-bitmap-surface {
    position: relative;
    isolation: isolate;
}

.air-bitmap-surface::before {
    content: "";
    position: absolute;
    inset: 0;
    z-index: -1;
    border-image-source: var(--air-surface-image);
    border-image-slice: var(--air-surface-slice, 6) fill;
    border-image-width: var(--air-surface-width, 6px);
    border-image-repeat: stretch;
    image-rendering: pixelated;
    pointer-events: none;
}