Adding and Refactoring the CSS Code

[bluzeey]

Hi Rajan , I was checking out this repository and I think the CSS Code could be more optimized. Particularly the navbar can be justified center.
Also it can be made more mobile-responsive

[Rajangrg]

Hi @bluzeey,

Thank you for your feedback, can you please give more clarification on CSS optimization as there are many ways that can be done.

Please feel free to make the changes and send me a PR I will be more than happy to merge into master if applicable.

Thanks