#texture

A razor background-image referencing a loose PNG/JPG renders in-editor (loose Assets are readable off the mounted filesystem) but goes blank in the published package, because loose non-compiled images are not auto-shipped. Add the disk glob to the sbproj Resources list; the wildcard matches the loose disk path, not the normalized asset path.

An image you write to FileSystem.Data at runtime (a per-save thumbnail, a screenshot) is not addressable from a CSS background-image URL -- those resolve against mounted content, not the user Data FS. Decode it into a Texture in code and assign Style.BackgroundImage instead.

SCSS background-image only resolves asset paths. Runtime Texture objects must be assigned via Panel.Style.BackgroundImage in OnTreeBuilt.

A repeating red "Texture manager doesn't know about texture ... default_mask ... returning error texture" pair on engine/RenderSystem is base-menu-addon noise mounted into every project, not your content. It repeats per draw call. There is no supported way to mute it from game code. Filter it visually.