Added parameter for display

[jkorff]

'displayType' is 'block' by default, emulating the usual CSS display property of the base version.

You can also set it to 'flex' if you want to restyle the popup.

When setting it to 'flex' you can use the following CSS (in addition to the existing CSS) to make the popup responsive:

#ouibounce-modal {
    justify-content: center;
    align-items: center;
    align-content: center;
}

Remove these styles:

#ouibounce-modal .modal {
    position: absolute;
    margin: auto;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
}

[jkorff]

This commit replaces CSS with classes which keeps the layers separate and allows for full flexibility.