made the site responsive

[Mitushi-23]

What is the change?

I have made the site responsive which includes navbar,team, projrcts, opportunities and contact-form.

Related issue?

closes: #49

Checklist:

Before you create this PR, confirm all the requirements listed below by checking the checkboxes [x]:

• [x] I have followed the Code of Conduct.
• [x] I have checked there aren't other open Pull Requests for the same update/change.
• [x] I have you tested the code before submission.
• [x] I have commented my code, particularly in hard-to-understand areas.
• [x] My changes generates no new warnings.
• [x] I'm Hacktoberfest'21 contributor.

Screenshots (if any)

[Chaitalishetty]

@Mitushi-23 Don't make a pr without getting it assigned.

[Mitushi-23]

@Chaitalishetty Can I make pull request now as the issue is now assigned to me?