HFI Calculator: Enhance clarity of de-selected row

**As a** *(User Type/Persona)* **I want** *(Feature/enhancement)* **So That** *(Value, why is this wanted, what is the user trying to accomplish)*

**Additional Context**
- Awaiting user input - will add a 4Grooming label when ready

**Acceptance Criteria**
- [ ] Given I am using HFI Calc., When I de-select a station, Then the available data still displays, a lighter grey font is used and the row is a grey colour to indicate a different state
- [ ] Given (Context), When (action carried out), Then (expected outcome)

**Definition of Done**
- [ ] Ready to Demo in Sprint Review
- [ ] Does what I have made have appropriate test coverage?
- [ ] Documentation and/or scientific documentation exists and can be found
- [ ] Peer Reviewed by 2 people on the team
- [ ] Manual testing of all PRs in Dev and Prod
- [ ] Merged

The issue names the HFI Calculator and station rows but no source files or tests. Start by locating the HFI Calculator UI and its station-selection behavior, then confirm the intended de-selected styling against the attached screenshot and acceptance criteria; done means data remains visible while the row and text clearly appear de-selected.

Written by the indexing model from the issue text.