[utils] Fix pseudo-element bounds in dev

[atomiks]

Pseudo-element hit-area expansion was skipped in every non-production build. This keeps jsdom on the safe path while allowing real development browsers to calculate pseudo-element bounds.

Root cause

The jsdom workaround was tied to NODE_ENV, so development browsers returned the element rect before reading pseudo-element styles.

Changes

• Replace the broad non-production guard with a jsdom-specific guard and fallback catch.
• Add coverage for the jsdom safe path and pseudo-element bounds calculation.

[pkg-pr-new]

• base-ui-tanstack-start

• vite-css-base-ui-example

  pnpm add https://pkg.pr.new/mui/base-ui/@base-ui/react@5000
  

  pnpm add https://pkg.pr.new/mui/base-ui/@base-ui/utils@5000
  

commit: 77ce714

[code-infra-dashboard]

Bundle size

Bundle	Parsed size	Gzip size
@base-ui/react	🔺+19B(0.00%)	🔺+5B(0.00%)

Details of bundle changes

Performance

Total duration: 1,402.17 ms +211.42 ms^(+17.8%) | Renders: 50 ⁽⁺⁰⁾ | Paint: 2,110.49 ms +329.24 ms^(+18.5%)

Test	Duration	Renders
Tabs mount (200 instances)	281.62 ms 🔺+52.17 ms(+22.7%)	4 (+0)
Select mount (200 instances)	173.90 ms 🔺+42.34 ms(+32.2%)	3 (+0)
Checkbox mount (500 instances)	86.54 ms 🔺+22.86 ms(+35.9%)	1 (+0)
Select open (500 options)	72.42 ms 🔺+22.45 ms(+44.9%)	14 (+0)
Popover mount (300 instances)	82.23 ms 🔺+17.57 ms(+27.2%)	1 (+0)

7 tests within noise — details

---

Check out the code infra dashboard for more information about this PR.

[netlify]

✅ Deploy Preview for base-ui ready!

Name	Link
🔨 Latest commit	77ce714
🔍 Latest deploy log	https://app.netlify.com/projects/base-ui/deploys/6a29162ca481ca00081e2f00
😎 Deploy Preview	https://deploy-preview-5000--base-ui.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.
🤖 Make changes	Run an agent on this branch

---

To edit notification comments on pull requests, go to your Netlify project configuration.