On 12/20/16 3:37 PM, Mark Legate wrote:
I wasn't satisfied with the clarity of my response so I detailed out the issue
further:
http://pastebin.com/pvLNXXip
The heart of the misunderstanding here is this bit:
4 - The element from which the value is propagated must have a used
value for 'overflow' of 'visible'.
Propagation to viewport happens on computed values (or specified; the
spec is not clear on this, but for overflow computed and specified are
the same). Then after that used values are determined. So in this case:
<html style="overflow:visible">
<body style="overflow:hidden">
The following things will happen:
1) The overflow on <html> is computed to "visible".
2) The overflow on <body> is computed to "hidden".
3) Per your item 2, the overflow on <body> is propagated to the
viewport, giving the viewport an overflow of "hidden".
4) Per your item 4, the used value of overflow on <body> is set to
"visible".
The reason for step 4 (your item 4) is that in this situation:
<html style="overflow: visible">
<body style="overflow: scroll">
the desired behavior is one single scrollbar, not separate scrollbars on
the viewport and the <body>.
-Boris
P.S. In case you care, the person you're responding to (dbaron) was
involved in writing the spec you're citing.
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