[bug] <title>Token Bridge chain select dropdown issue

[bjeschke]

Is there an existing issue for this?

• [X] I have searched the existing issues

Current Behavior

Browser: Firefox on Mac OS

When you open the dropdown on https://portalbridge.com/advanced-tools/#/nft you cannot select the upper chains because the navigation overlaps the dropdown

Expected Behavior

The dropdown should overlay everthing else.

Steps To Reproduce

https://portalbridge.com/advanced-tools/#/nft

open dropdown to select chain. Try to choose the upper chains

Environment

- OS: Mac OS
- Wallet:
- Browser: Firefox

Anything else?

No response