Improvement in the Home Page and Change in Font in theme settings

[Harsh-Udai]

Hello ,
My name is Harsh Udai,

I have checked the whole repo, and i want to contibute in this repo to make this platform more effective.
This is my first contribution/feature request in GSSoC 21.

i have gone through the whole Manthan Platform, and i have observed some things that's need to be updated.

1. In Mathan's Home page, if we see the page in smaller resolution, the copyright bar appears 2 time, which i think only 1 should be fine, and the alignment of text is also overlapping with the green background.
   

Overlapping of text

2. when we open theme change pallete, the font appears to be different from the whole platform.
   

The font of Heading.

3. the options github in the app bar is opening the github page in same tab, if we set this to open in new tab, will be more better, because when we click on github it directly opens the github, therofore sometime it may be problematic, as ( react states changes to default after re-render).

Please assign me this task, therofore i can start the work,
Thank you

@Kathuria @atulya2109 @aavishkarmishra

[Harsh-Udai]

@aavishkarmishra hello, i have created PR please review it.