https://drafts.csswg.org/css-sizing/#valdef-width-auto says
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auto
For width/height, specifies an automatic size. See the relevant layout module for how to calculate this.
For min-width/min-height, specifies an automatic minimum size. Unless otherwise defined by the relevant layout module, however, it resolves to a used value of 0.
For backwards-compatibility, the resolved value of this keyword is zero for boxes of all [CSS2] display types: block and inline boxes, inline blocks, and all the table layout boxes.
The 3rd paragraph doesn't mention width/height nor min-width/min-height, so it seems it applies to all of them. However, the resolved value of width/height: auto for css2 boxes is not 0 in general, see https://drafts.csswg.org/cssom/#ref-for-propdef-width
The 3rd paragraphs should be merged into the 2nd, or repeat that it's for the min-width/min-height properties.
https://drafts.csswg.org/css-sizing/#valdef-width-auto says
The 3rd paragraph doesn't mention
width/heightnormin-width/min-height, so it seems it applies to all of them. However, the resolved value ofwidth/height: autofor css2 boxes is not 0 in general, see https://drafts.csswg.org/cssom/#ref-for-propdef-widthThe 3rd paragraphs should be merged into the 2nd, or repeat that it's for the
min-width/min-heightproperties.