- Remove .insertr-default-style special styling (blue background, border, dot indicator)
- Make ALL buttons use .insertr-style-preview with unified appearance
- Maintain authentic style previews in isolated .insertr-style-sample layer
- Bold buttons show bold text, .brand buttons show green uppercase text, etc.
- Eliminate visual inconsistency between semantic and detected style buttons
- Simplify CSS by removing ~50 lines of duplicate button styling
- Provide consistent professional toolbar appearance across all formatting options