Things to watch out for

Everything here is known and either handled or refused. It is listed so that when you meet it, you recognise it instead of debugging it.

The bake is one picture

Whatever the cascade resolved to at capture time is what ships. A modifier class added later cannot change it. See preparing your UI.

State variants swap in instantly

A baked hover replaces the base texture the moment the state changes. If the property was under a transition, that transition is gone. The build warns with RZ002; set strictTransitions: true to make it an error.

Some effects can never be baked

mix-blend-mode and backdrop-filter do not composite source-over, so no texture can reproduce them against an arbitrary backdrop. There is no approximation mode. The build refuses with RZ001; remove the marker or remove the property.

filter and mask-image may survive the bake

If anything inside the element is still live, the effect has to stay live too, and it still costs a pass every frame. The build tells you which case you are in (RZ025). Marking a fully static subtree as element mode is usually the fix.

Gradients and 9-slicing do not mix

A 9-slice stretches its edges and centre, so anything that varies along the stretched axis comes apart (RZ005). Fixed-size elements can use flat mode and keep the gradient.

Very small elements cannot slice either: when the element is narrower than its two corners put together, there is nothing between them to stretch. Those are baked flat at their measured size (RZ024).

Textures cost VRAM

Every state is a separate texture. Four panels at four different pixel sizes are four textures, because they are four different pictures. The build reports the total against textureBudgetMB and names the worst offenders (RZ006).

Do not use data-rasterize-states to fix a matching problem: it bakes another texture for no visual benefit, and RZ016 will say the variant was pointless.

getComputedStyle cannot see the decoration

The decoration is a ::before, and getComputedStyle(el, '::before') returns none on this engine even while it is painting. Read rz/rasterize.css or inspect the rendered output instead.

Verification does not cover decorations yet

verify: true isolates each asset by toggling a node, which no longer exists now that decorations are pseudo-elements. Rather than report a pass it did not earn, it refuses to run when any decoration asset is present.

The build audit still compares the whole page on every build (RZ023), which is the check that matters most.

Engine quirks the plugin works around

You should not normally see these, but they explain what is in the generated CSS:

• z-index: -1 and a forced stacking context. An absolutely positioned pseudo-element would otherwise paint after in-flow content and cover your text.
• A translateX on <button> decorations only. cohtml places a pseudo-element’s left edge at the button’s own edge regardless of the offset. Vertical offsets and width are fine.
• State variants are captured with real input, because CSS.forcePseudoState is accepted by this engine and does nothing.