Bug: Move header up on TwoColumPanel when shrinks

### Steps to reproduce

1. Open https://cauldron.dequelabs.com/components/TwoColumnPanel
2. Resize window to 720
3. Instead of the header staying on the top line, it jumps to a second line.

> 720px (header "One" inline correctly)

< 720px (header "One" jumps onto a separate line

### Expected Behavior

Header to remain on top line

### Actual Behavior

Header jumped onto new line

### Version

I dunno

### What browsers are you experiencing the problem on?

_No response_

### Relevant log output

_No response_

### Anything else we should know?

Additional information