💡Pet images are not displaying in blog sections

**Is your feature request related to a problem? Please describe.**
I'd like to address an issue where some pet images are not displaying in the blog sections. Additionally, I'd like to enhance the style of each blog page.

here is the problem:

**Describe the solution you'd like**
The images are not displaying because the file extensions in the HTML code are incorrect.
For styling, I would like to add a dark and light mode, consistent with the rest of the site, and improve the appearance of the navigation bar to make it more visually appealing.

This would be my first contribution, and I would like to help resolve the issue mentioned.
Please assign me this issue