The empty `MultiSelectCombobox` rendered ~46px tall next to the fixed
40px `Input`, breaking form rows that place them side by side, most
visibly the IdP sync mapping fields (`/organizations/{org}/idp-sync`,
IdP org sync, template/parameter forms).
## Root cause
#27821 removed MUI's `CssBaseline` and enabled Tailwind preflight
(`corePlugins.preflight` was previously `false`). Preflight sets `input
{ line-height: inherit }`, so the combobox's inner cmdk input started
inheriting the wrapper's `text-sm` 24px line instead of the browser
default. With its `py-2.5` padding the empty combobox computed to 24 +
20 + 2 = 46px, while `Input` stays pinned at `h-10`.
This is a sibling of the `ModelSelector` regressions fixed in #28399,
but in the shared combobox primitive, so that fix could not reach these
pages.
## Fix
- Pin the inner cmdk input to `leading-5` and reduce the empty-state
padding to `py-2` (20 + 16 = 36px row).
- Make the wrapper a `flex flex-col justify-center` so the row centers
within `min-h-10`, giving exactly 40px when empty while the selected
state still grows with its badges.
## Validation
- Red-green verified with a temporary geometry probe story: combobox
wrapper 46px before, 40px after (Input 40px in both). The probe was not
committed (FE10) and no new story ships with this PR per review.
- `pnpm test:storybook` for `MultiSelectCombobox`, `IdpSyncPageView`,
`IdpOrgSyncPageView`, and `DynamicParameter`: all pass.
- `biome check` and `tsc -p .` clean.
> 🤖 This PR was written by Coder Agents on behalf of @tracyjohnsonux.
TJ
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