* Add back "Resize to window" link.
* Add Z shortcut for resize to window link (mnemonic: Z for zoom image).
* Resize images to screen width by default on both desktop and mobile.
* Make it so that notes are nested directly inside the .image-container
element with the image, instead of inside a separate .note-container
element. This means .image-container and .note-container are now the
same element. This is so that the size of the .note-container is
driven by the size of the image, which ensures that notes are
automatically resized as the image is resized.
