[css-break][css-box][css-text][css-position] percentages and fragmentation

[frivoal]

There are a few properties where percentages are resolved against the size of the container. What if the container is fragmented? Each fragment is likely to have a different block size, and could even have different inline-sizes. How are these percentages then resolved? Per fragment? Based on the first fragment? Something else? For instance:

• margin-*, padding-* (both have potentially multiple instances, due to box-decoration-break)
• text-indent
• left, right, top, bottom
• (I'm sure there are more)

[frivoal]

Actually, this is probably covered by https://www.w3.org/TR/css-break-4/#varying-size-boxes:

When a flow is fragmented into varying-size fragmentainers, the following rules are observed for adapting layout:

• Layout is performed per-fragmentainer,

Though maybe a note about what that implies for percentages might be nice.