Built-in CSS

Built-in CSS should match the current Survey Link rendering contract. Preview coverage needs examples for base question types, attribute display styles, numeric display styles, validation errors, and question name badges. Public Survey Link falls back to the built-in Classic Clean preset only when no explicit safe saved style selection can be used.

Update checklist

• Add preview coverage when a new rendered class or display style is added.
• Keep built-in CSS language-independent where possible.
• Avoid guide copy in Survey Link UI; use icon-first feedback for respondent-facing guidance.
• Keep class names stable for authored theme overrides.