When the Inspector window is resized to its minimum width, "Down" button text is clipped under TMP StyleSheet, refer to the attached screenshot.

Steps to repro:
1. Create a new Project
2. Project > Create > TextMeshPro > StyleSheet
3. Project > TMP StyleSheet > inspector
4.Resize Inspector window to its minimum width

Actual Result:
Down button text is clipped

Expected Result:
Down button text visible clearly

Note: Down and Up buttons are introduced in TMP package 3.0.0-preview.1 with Unity 2020.1.0a11

Reproducible in:
2020.2.0a16, 2020.1.b14, 2020.1.0a11 with Package Version 3.0.0-preview.14, 3.0.0-preview.1

Environment:
Windows 10 & macOS 10.15.