Fix 545: text color of 'about us' option and 'news' option

[Lakshya0257]

Fixed the issue raised in #545

Issue

Navbar tabs were showing two different colors in two different window sizes.

Fix

• Fixed by modifying the nav.html without affecting any other behaviour.

Output

[therealharshit]

@Lakshya0257 I think it would be much better if it looks like

On both the screen size.

[Lakshya0257]

@therealharshit I have modified according to your requirements, kindly review it now.

[therealharshit]

@Lakshya0257 the changes you made didn't fix this issue, it has also also affected the previous behavior of navbar.
Vedio:

nav.mp4

[Sushant0124]

@therealharshit Is the issue is still there??

[pikurasa]

@Sushant0124 once you get this "camera ready", please put it on a new branch and open up a new PR. It's a very important habit to get into.

Please refer to https://github.com/sugarlabs/sugar-docs/blob/master/src/contributing.md#making-commits for best practices.