- Add --line-height CSS variable (18px = 12px font * 1.5)
- Convert all padding/margin to use var(--line-height)
- Remove fractional values for terminal-like consistency
- Fix gap between consecutive tool executions
- Remove extra padding from error-text and model-change
- Fix thinking toggle to show 'Thinking ...' when collapsed
- Remove top padding after timestamps in assistant messages
- Remove bottom padding from assistant-text