I've been using CSS for almost six years. During this period,
sometimes I wondered about some obscure details of CSS specifications.
These details are listed below.
• LAYERING AND STACKING ORDER
When elements are absolutely positioned, it's crucial to determine how
they should be overlapped. The problem is that most browsers don't
agree on how this stacking order should be displayed. For example,
consider the following:
view plainprint?
• #container {
• position: relative;
• }
•
• #child {
• position: absolute;
• z-index: -1;
• }
In this case, this element should not be displayed, since we gave to
it a negative z-index. Unfortunately, some browsers don't consider 0
as the starting value for the stacking order, so this rule won't work
in some cases.
• CLEARING AND CONTAINING FLOATS
As developers, we all know a series of techniques for clearing and
containing floats, which includes:
• overflow:auto/hidden
• position: absolute
I mentioned only those that keep me wondering about how they actually
work. We all know that floats make vertical space collapse. However,
when the former declaration is applied to a parent element, browsers
automatically expand the available vertical space to include floats,
even when those floats have no stated height. So we should assume that
browsers automatically calculate the height of these elements and
react accordingly.
Instead, the latter declaration is even more complicated. We just
assume that the vertical space is calculated again according to the
actual height of floats, but I don't think this is a sufficient
explanation. CSS specifications don't say much about this issue. More
precisely, they don't say much about the general problem of clearing
and containing floats.
• NEGATIVE MARGINS
The question is: "How negative margins affect the computation of the
overall dimensions of a containing block?" By subtracting a given
length, both horizontal and vertical, what is the computed value of
the width and height of a containing block? This should be further
investigated.
http://www.css-zibaldone.com
http://www.css-zibaldone.com/test/ (English)
http://www.css-zibaldone.com/articles/ (English)
http://onwebdev.blogspot.com/ (English)
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