Margin issues in mobile view

[phamduylong]

The header Blog posts doesn't have any spacing from the viewport. I think this is caused by this row class from Bootstrap. It applies negative margins

I can throw a fix quickly if this is approved as a solution.

[devlead]

Happy to take contributions to the site.

The code is here
https://github.com/LitJSON/litjson.github.io/tree/develop/input

[phamduylong]

@devlead FYI I threw a PR for this issue