Lack of padding on each side in the header

<img width="500" alt="image" src="https://github.com/audacity/audacity.github.io/assets/70063970/f31512d0-d8e4-4832-9faa-6405895a32c5">

Browser:
[Version 1.63.174 Chromium: 122.0.6261.128 (Official Build) (arm64)](https://brave.com/latest/)
OS: macOS 14.3
