fix(pageHeader): menu button overflow issue on small screens

[devadula-nandan]

Closes #6415

fixes menu button overflow issue in firefox in small screen

What did you change?

packages/ibm-products-styles/src/components/PageHeader/_page-header.scss

How did you test and verify your work?

storybook, firefox

[netlify[bot]]

✅ Deploy Preview for ibm-products-web-components ready!

Name	Link
🔨 Latest commit	9f0378c1d71809f30041d5c4cdf04d3845cbe6ea
🔍 Latest deploy log	https://app.netlify.com/sites/ibm-products-web-components/deploys/67444c1b39e4d8000875805b
😎 Deploy Preview	https://deploy-preview-6502--ibm-products-web-components.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

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

[netlify[bot]]

✅ Deploy Preview for carbon-for-ibm-products ready!

Name	Link
🔨 Latest commit	9f0378c1d71809f30041d5c4cdf04d3845cbe6ea
🔍 Latest deploy log	https://app.netlify.com/sites/carbon-for-ibm-products/deploys/67444c1be83ec70008a224e2
😎 Deploy Preview	https://deploy-preview-6502--carbon-for-ibm-products.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

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

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 79.65%. Comparing base (473af0f) to head (9f0378c).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #6502 +/- ## ======================================= Coverage 79.65% 79.65% ======================================= Files 394 394 Lines 12871 12871 Branches 4257 4257 ======================================= Hits 10253 10253 Misses 2618 2618 ``` | [Components](https://app.codecov.io/gh/carbon-design-system/ibm-products/pull/6502/components?src=pr&el=components&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=carbon-design-system) | Coverage Δ | | |---|---|---| | [ibm-products](https://app.codecov.io/gh/carbon-design-system/ibm-products/pull/6502/components?src=pr&el=component&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=carbon-design-system) | `∅ <ø> (∅)` | | | [ibm-products-web-components](https://app.codecov.io/gh/carbon-design-system/ibm-products/pull/6502/components?src=pr&el=component&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=carbon-design-system) | `∅ <ø> (∅)` | |

---

🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests
• JS Bundle Analysis - Avoid shipping oversized bundles