Fix mobile primary screen: search bar should match desktop rendering

[dpshde]

Currently on mobile, the primary screen search bar behaves differently than desktop. The search bar should render similarly to desktop by default, but maintain the full-screen mode when focused.

Current Behavior:

• Mobile has different default rendering
• Search bar appearance inconsistent with desktop

Expected Behavior:

• Search bar renders like desktop on primary screen
• Full-screen mode activates only when user focuses/taps the search input
• Maintains existing full-screen functionality for better mobile UX

Tasks:

• Review current mobile CSS and layout
• Align default mobile search bar with desktop appearance
• Ensure full-screen mode triggers correctly on focus
• Test on various mobile devices/screen sizes