- Session title: font-title (CMU Serif bold) at text-2xl, per the mock. - MessageResponse's markdown container now carries .lh-prose (Source Sans 3 + emphasis tokens) on every markdown surface; labels stay JetBrains Mono. Unlayered plain CSS beats the text-sm utility. - PhaseChip + PhaseDivider sizes now pull from the declared text ladder (text-xs) instead of pixel literals.