Issues #5, #7: Frontend fixes

fluffy-frontend/src/App.css

fluffy-frontend/src/App.tsx

fluffy-frontend/src/ProjectDevices.tsx

fluffy-frontend/src/ProjectPermissions.tsx

fluffy-frontend/src/ProjectRoles.tsx

fluffy-frontend/src/Toasts.tsx

fluffy-frontend/src/WhenBackendAvailable.tsx

fluffy-frontend/src/hooks/mqtt.hooks.ts

fluffy-frontend/src/utils/Components.tsx

fluffy-frontend/src/utils/InlineForm.tsx

fluffy-frontend/src/utils/Select.tsx