Adding feature: Different themes like dark mode and others

[subhranshuchoudhury]

• Assign me this work.
• Pls add label for hacktoberfest.
• @DhanushNehru

[JilsT]

@DhanushNehru
If this feature hasn't been added or the issue hasn't been resolved,
Please assign me the work.

[DhanushNehru]

Since this issue was assigned & open for more than 7 days assigning to @JilsT