Redesigned and Improved 404 page UI

Explanation

[x] The PR fixes the issue that title starts with #75.
[ ] The PR explanation includes the words "Fixes #bugnum: ..." ( or "Fixes part of #bugnum" if the PR only partially fixes an issue ).
[x] The PR does not contain any unnecessary auto-generated code from Android Studio.
[x] The PR does not break any part of the existing code.
[x] The PR creator have carefully read & adhere to the contributing guidelines of the project.
[x] The PR is raised for an issue that has been assigned to you.
[x] The PR is made to the branch that's called "develop".
[x] The PR is raised from a branch that is up-to-date with "develop".

Please review and merge this issue under GSSOC '22.

Thanks!