https://gerrit.wikimedia.org/r/#/c/279687/
This greatly improves our mobile support by doing various things,
including:
- Hide the image until it's positioned to avoid jerking movements
- Take into consideration whether a position was provided or not
- For portrait photos (height is greater than container) reposition
to -10% on basis that most portraits put the face in this position
- Add a bottom transparent border for white lead banners
- Add a panorama class to distinguish between portrait photos and panoramas
in the styling
- Reposition panoramas at -25% when no center position given