Pages, documents and files fit phones and tablets

Covers keep their proportions as the screen narrows: a tablet in portrait or a phone shows the whole cover, smaller, never a cropped middle of it.
New page: the template gallery never runs off the side of a phone (a template's preview with a table used to widen it), lists the templates in one column on a phone, and on a touch screen opens on the templates, not in the title, so the keyboard doesn't cover them.
Touch screens: the cover's tools, Add icon and Add cover, and an embed's Show as, Replace and Remove no longer wait for a hover. Every button in the page's bar, head and body is big enough for a finger, text fields never make the page zoom in, and nothing reads under 12 px.
Tablets get the editing toolbar above the keyboard that phones have (add a block, the block menu, format, undo), as a bar in the middle of the screen.
Files: an image opens fitted to the screen (tap it for full size), two fingers zoom a PDF's pages, and the video player and spreadsheets are sized for a finger.
See Colours, columns and block tools and Supported file types.