Added Custom Scrollbar - Githubissues

Explanation

Added Custom Scrollbar according to theme.

[x] The PR title starts with "Fix #bugnum: "followed by a short, clear summary of the changes. ( If this PR fixes part of an issue, prefix the title with "Fix part of #bugnum: ...")
[x] 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".