Fix search scroll bar issue on navbar (#3998)

Limit mobile drop downs to 1/3 screen height

Closes #3996 

### UI Changes (

<img width="1541" height="1251"
alt="{5866A763-EE40-4E8B-B186-8FD28927F053}"
src="https://github.com/user-attachments/assets/deb1ca76-54df-4cb5-9662-471c914a9f8e"
/>
<img width="546" height="1008"
alt="{9395DF85-6FE0-4359-AA81-A657AC17DF15}"
src="https://github.com/user-attachments/assets/b67ce1c0-5736-4efe-9927-eedf1892e5f9"
/>

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Co-authored-by: Connor Yoh <connor@stirlingpdf.com>