nav-footer is scrolled outside of the visible are on mobile

**Describe the bug**
The nav-footer (with the 1/2/3) buttons should always be visible on mobile, when the nav bar is open. But for some reason the site ignores the height of the browser bar / URL bar when calculating the position. Only when that bar is collapsed (by scrolling upwards) is the nav-footer actually visible.

**To Reproduce**
Steps to reproduce the behavior:
1. Open the site on any mobile device
2. Open the nav bar by clicking on the hamburger icon

**Expected behavior**
nav-footer should be visible

**Screenshots**
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**Desktop (please complete the following information):**
- OS: Android
- Browser: Chrome, Firefox Focis

**Smartphone (please complete the following information):**
- Device: Pixel 7A

**Additional context**
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