Direct design edits use your stored brand tokens and active library images, not arbitrary CSS. The constraint keeps one-off changes from quietly creating a second, inconsistent design system inside an email.
The four supported token kinds
The direct-token route accepts exactly:
palette_color— a color token already present in your brand design system;type_scale— a stored email-safe type-size token;alignment—left,center, orright, where the block supports it; andlibrary_image— the UUID of an active image in your workspace’s brand library.
The Workbench resolves a token to its stored value. Unknown palette or type-scale IDs are rejected, as are image IDs that are inactive, belong to another workspace, or are not supported image kinds.
Text is still editable
Edit mode allows inline changes in supported paragraph, list, and heading blocks. Those changes pass a constrained HTML envelope and the same changed-block truthfulness check used by other targeted edits.
When a token does not fit
Not every token applies to every block. For example, an image token needs an editable standalone image block, and button alignment is controlled by its layout wrapper. If the block cannot take the requested token, use an annotation pin instead.