Bug Bash: UI Consistency & Experience

## Bug Bash: UI Consistency & Experience
Assigned To: Kristy, Hande
### Bug Fixes:

- [x] Font inconsistencies
- [x] Headers disappearing on scroll
- [x] Admin visibility for standard users
- [x] Chart readability + axis issues
- [x] Preview rendering bugs 

### Font Inconsistencies
Fonts render differently across pages and reports.

<img width="214" height="204" alt="Image" src="https://github.com/user-attachments/assets/085bb30c-4fa4-4571-87dd-9a251e13f6dc" />

<img width="330" height="289" alt="Image" src="https://github.com/user-attachments/assets/c2bbd702-8400-4e5c-a844-81ec0748bd20" />

<img width="472" height="82" alt="Image" src="https://github.com/user-attachments/assets/c1e79cdd-3b08-4327-8899-f4cf596ed93f" />

### Headers Disappearing on Scroll
Headers vanish when scrolling, making navigation harder.
Expected: Sticky or consistently visible headers

### Admin Visibility for Standard Users
Standard users can see and interact with admin page elements. When the user's permission is not an admin, do not show the Admin page on the navbar.

### Chart readability + axis issues
Make sure the chart axis and title don't overlap.
<img width="410" height="520" alt="Image" src="https://github.com/user-attachments/assets/55bed6ab-9ad1-447d-8477-1a884cd81b98" />

### Preview rendering bugs 
- Fixed squished previews
- Play around with filters and make sure all previews work. Fix previews that do not work.

**Squished Previews**
<img width="286" height="175" alt="Image" src="https://github.com/user-attachments/assets/51b9e3eb-e0d0-4bf1-8e61-17ed40e8a220" />

**Preview messes up the y-axis**
<img width="487" height="312" alt="Image" src="https://github.com/user-attachments/assets/039a88cf-4c4b-4f4d-86c1-49cc6d155452" />

Navigation Menu

Uh oh!

Bug Bash: UI Consistency & Experience #93