Hello Brooke H23A
Thank you for posting in Microsoft Community! We are happy to assist.
Based on your description, The Theme is not functioning properly. Feel free to correct me if I misunderstood.
You can check the Text size and spacing on the settings and set them to small, this may fix the issue for you
If the issue still persist, you can repair the New Outlook or even Reset it. Here are the steps to do so:
Open windows Settings
Click Apps
Click Outlook (new) > Advanced Options
Click Repair
If the repair does not fix the issue
Click Reset
NOTE: If you reset the App, the data will be deleted
I hope the above information will be helpful. Please feel free to let me know if you have any other concern or if I get you wrong. Glad to assist you. We sincerely appreciate your patience and cooperation. Thanks for your precious time!
Note: Please understand that our initial reply may not always immediately resolve the issue. However, with your help and more detailed information, we can work together to find a solution.
Best regards
Microsoft Community Moderator