fix: correct missing basename on react router

[asherlloyd]

Description

The basename was missing from the React Router, causing issues with page reloads.

Edit: this also corrects a style change that didn't get added in #145.

Reason

Restores the missing basename property on the React Router.

How this has been tested

Locally: via the React frontend using yarn dev and the built binary via yarn build in conjunction with the Django API.

Types of changes

• [ ] New feature (adds functionality)
• [x] Bug fix (fixes an issue)
• [ ] Breaking changes (causes defects to existing pieces)

Screenshots

Checklist:

• [x] I have read and complied with the CONTRIBUTING document
• [x] The changes I've made follow the existing code style and formatting requirements
• [ ] My changes require updates to the documentation, which I have modified accordingly