Thanks for getting back to me so quickly.
No luck with that CSS, unfortunately. The search box will remain rectangular until a character is entered, then it’ll go back to fully rounded corners each time a key is pressed. A workaround I’ve found for now is to set the border-radius to 30px, which results in a rounded search box. Changing the border-radius to smaller values will have that be the “default” shape, so having this be a fully rounded rectangle will disguise the issue.
The new js files work like a charm, thank you!