The `info` property seems to refer to the image size, not the rotation center in the backdrop library. So if it exists, halve it to find the center.

Towards #18

Remove MediaLibrary helper since it is now unused

The inline css method gives us nothing that CSS modules can't give us. This puts the project more in line with the way www works, and makes CSS actually readable.

Using class names gives us full control of the modal styles.