Make more responsive

I think this still needs work but I'd appreciate feedback!

I'm aiming for this to look natural on both tablet and phone sized devices.

Fixes #7 
`affix` class is required, it basically puts the info card in fixed position even though we scroll through the page, fixing the position of info card was intentional by design.

All you need to do is just make `position: relative` on lower widths as follows:

```css
@media only screen and (max-width : @bootstrap-md-cutoff){
    .card-wrapper {
        position: relative;
    }
}
```

If you do this you can revert all the below changes & also you can get rid of `center-block` class.