Placeholders
What the screen shows while the figures are still on their way. The shape matches what is coming, so nothing moves when the data lands.
Lines of text
three widths, so it reads as prose rather than bars
Loading
A figure tile
the same box the number will sit in
A table
rows of the height they will really be
Why not a spinner
A spinner says something is happening. A placeholder says a table of five rows is coming, and it will start here — so the eye has already found its place by the time the figures arrive, and the page does not jump.
Two rules Coffer follows: the placeholder is the same height as the real thing, and it is hidden from screen readers — a reader hears one Loading, not forty empty boxes. The pulse stops for anyone who has asked for less motion.