Resizing Vertical Bar

User story

As a user, I want to be able to resize the code area to adjust its width using a vertical bar. Resizing the code area should affect the available space for the preview.

Acceptance criteria

• A vertical bar with an icon is displayed between the code area and the preview.
• The user can click and drag the bar to adjust the width of the code area.
• Resizing the code area should dynamically adjust the available space for the preview.