[BUG] Fix mergesort navlink and bubblesort css

[vansh-codes]

Description
(Description about the issue)

• mergesort page is not available after going to a algorithm as its href is wrong in the code, i would love to fix it for every page where its not available
• Ex to verify: go to Algorithm in the navbar, select Bubble Sort from the dropdown, now on the BubbleSort page again go on Algorithm in the navbar and select mergesort :: now its not available
• Bubble Sort page algorithm description is not visible correctly, I would fix that
• Add faivon on every page, its missing on algorithm pages (check here: https://visual-sort-pink.vercel.app/Algorithm/Bubble.html)

Use Case
(Use cases and benefits)

• page availability

Screenshots
(Screenshots of the issue or reference)

Additional Context
(Any other context about the problem)

[MastanSayyad]

I was planning to solve it myself, but you can go ahead @vansh-codes