- Shipped
- September 11, 2026 at 1:49 AM UTC
- Author
- Kamo
- Commit
- 3f80026
I18nProviders handed the Geist font to createTheme as an overlay, and overlays are merged in after the theme is built. By then MUI has already written its Roboto stack into every typography variant, so the overlay replaced only the top-level fontFamily, and every Tab, Button, TextField and Typography kept "Roboto, Helvetica, Arial". Roboto is loaded nowhere, so MUI text drew in Helvetica on a Mac and Arial on Windows, beside Geist in everything else. The only MUI parts in Geist were the few that read the top-level field, such as Chip and Tooltip. The font is now the typography option, so it reaches every variant. MUI then also drops the letter-spacing it tunes for Roboto, as it does for any other face. The Calendar and Contacts theme scopes build on this theme and follow it. Measured in Chrome through the real providers: 15 of 16 probed MUI elements were drawn in Arial's stand-in before (the Chip was the one in Geist) and all 16 in Geist after. Text widths move between -7% (buttons, which lose the Roboto tracking) and +6% (bold headings); heights are unchanged, and both Interaction Center tab strips still fit.