Fix slider arrow styling for better visibility

[ishwari1201]

📝 Description

This PR improves the visibility and styling of the slider arrows in the product carousel.
Previously, the arrows were hard to see on certain product images.
This update adds better contrast, background, hover effects, and proper positioning to make the arrows more visible and user-friendly.

Changes made:

• Added semi-transparent background (rgba(0,0,0,0.4)) to the arrows.
• Increased z-index so arrows appear above the images.
• Added hover effect (rgba(0,0,0,0.7)) for interactivity.
• Adjusted padding, border-radius, and cursor styling.

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Fixes #322

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✅ Checklist Before Submitting

• I’ve tested the code locally and it works as expected
• I’ve followed the code style and contribution guidelines

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