Leonel Silva wrote:
Hola a todos,
Alguien conoce que navegadores soportan CSS2? o algún link donde pueda leer
algo al respecto.
Lo que vos pedís está aca [1] y mientras buscaba eso, me topé con este
artículo [2] que es muy interesante y completo, pero en particular
destaco la sección que habla sobre las actuales limitaciones del CSS,
incluyendo una que se habló hace pocos dias en la lista, de no poder
seleccionar el padre de un elemento.
CSS limitations
Most problems attributed to CSS are actually results of browser bugs or
lack of support for CSS features. The most serious offender among
current browsers is Microsoft Internet Explorer
<http://en.wikipedia.org/wiki/Internet_Explorer>, whose version 6 lacks
support for about 30 percent of CSS2 properties, and, more
significantly, misinterprets a significant number of important
properties, such as "|width|", "|height|", and "|float|".
However, current CSS specifications do have some genuine shortcomings.
Selectors are unable to ascend
CSS offers no way to select a parent or ancestor of element that
satisfies certain criteria. A more advanced selector scheme (such as
XPath <http://en.wikipedia.org/wiki/XPath>) would enable more
sophisticated stylesheets.
One block declaration cannot explicitly inherit from another
Inheritance of styles is performed by the browser based on the
containment hierarchy of DOM elements and the specificity of the
rule selectors, as suggested by the section 6.4.1 of the CSS2
specification [3]
<http://www.w3.org/TR/CSS2/cascade.html#cascading-order>. Only the
user of the blocks can refer to them by including class names into
the |class| attribute of a DOM element.
Vertical control limitations
While horizontal placement of elements is generally easy to control,
vertical placement is frequently unintuitive, convoluted, or
impossible. Simple tasks, such as centering an element vertically or
getting a footer to be placed no higher than bottom of viewport,
require complicated and unintuitive code.
Absence of expressions
There is no ability to specify property values as simple expressions
(such as |height: 100% - 3em + 4px;|). However, that can be achieved
by, |height: 100%; margin: -1.5em 0; padding: 2px 0;|.
Lack of orthogonality
Multiple properties often end up doing the same job. For instance,
position, display and float specify the placement model, and most of
the time they can't be combined meaningfully. A |display:
table-cell| element cannot be floated or given |position: relative|,
and an element with |float: left| should not react to changes of
|display|.
Unexpected margin collapsing
Margin collapsing is frequently not expected by authors, and no
simple side-effect-free way is available to control it.
Float containment
CSS does not explicitly offer any property that would force an
element to contain floats. Multiple properties offer this
functionality as a side effect, but none of them are completely
appropriate in all situations.
Lack of multiple backgrounds per element
Highly graphical designs require several background images for every
element, and CSS can support only one. Therefore, developers have to
choose between adding redundant wrappers around document elements,
or dropping the visual effect. This is addressed in the working
draft of the CSS3 backgrounds module,[4]
<http://www.w3.org/TR/2005/WD-css3-background-20050216/#layering>
but widespread implementation is unlikely for several years yet.
Inability of children to override some properties set on a parent
This problem affects publishing sites where portions of the same
page are often written by different vendors. For instance, if one
individual sets overflow:hidden on one element, this can't be
overridden within a child element. Although this makes sense in a
single-author environment, this can negatively affect a multi-author
environment where /most/ of the content should be contained, but
there's a menu that, by design, has to escape out of container.
Being able to explicitly set an override in a case like this would
be useful, since the only way to do this currently is by using
Javascript to manipulate the DOM. Another example is not being able
to override relatively positioned parents set by a different vendor
on the same page, so that the absolutely positioned child elements
are not appearing in the correct location.
--
Martin Szyszlican
www.ylisto.info
[1] http://en.wikipedia.org/wiki/Comparison_of_layout_engines
[2] http://en.wikipedia.org/wiki/Cascading_Style_Sheets
[3] http://www.w3.org/TR/CSS2/cascade.html#cascading-order
[4] http://www.w3.org/TR/2005/WD-css3-background-20050216/#layering
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