Holographic effect

Nothing here is an actual hologram. The look imitates embossed diffraction foil: the stuff on holo trading cards, bank card security patches, and 90s sticker sheets. Its signature is two things moving together as the card tilts: hard repeating rainbow bands (from the microscopic grooves splitting light) and a bright specular sweep riding over the top. Iridescence is the quiet material cousin; holographic is the loud manufactured version.

The web recipe is a stack. Base artwork, then a repeating linear or conic rainbow gradient in mix-blend-mode: color-dodge or hard-light, then a sparkle layer (tiled noise or a fine dot pattern) masked to the same shape, then a broad white highlight. Everything shifts against pointer position or device tilt, usually with a small 3D rotation on the card itself. The CSS Pokemon card demos that went viral in 2022 are the reference implementation everyone copies.

Two gotchas. It is most convincing in motion. A still view can carry it, since the diffraction bands and the specular sheen are visible standing still, but the whole character of foil is how it answers a change of angle, so a surface that cannot tilt or track a pointer sells it far more weakly. And it destroys text contrast, because color-dodge blows out anything light underneath. Keep type off the foil, or clip the effect to a border, badge, or background panel.