HTML and CSS Reference
In-Depth Information
Within a text flow, XHTML Basic also supports all of the content-based
style tags, including <abbr> , <acronym> , <address> , <cite> , <code> , <d-
fn> , <em> , <kbd> , <q> , <samp> , <strong> , and <var> . But given the paucity
of fonts on most mobile devices, especially mobile phones, a mobile
browser may be hard-pressed to even have more than one way to rep-
resent all these tags. This warning also applies to the heading tags, as
it is highly unlikely that most mobile phones can offer six font sizes to
distinguish the six heading tags.
Device font limitations also force the XHTML Basic standard to rule out
the physical style tags, such as bold and italic text. With no guarantee
that those styles will be available, it would be misleading to support the
equivalent tags. Bidirectional text also is not supported; many mobile
devices have a hard enough time rendering conventional text flows.
XHTML Basic has a strong focus on using stylesheets to manage the
presentation of your mobile content, but not within the context of the
page itself: the <style> tag itself is not supported. Instead, XHTML Basic
defers to external stylesheets and, to support them, includes the <div>
and <span> tags so that you can delimit your content and apply styles to
it as needed. Use the class attribute to associate a style with that text.
Of course, XHTML Basic also supports the <a> tag so that you can link
your pages to other documents. Images, objects, and scripting
Although you should use it very judiciously, XHTML Basic does include
the <img> tag. You should never drop images into your documents
without due consideration, and even more so for mobile browsing, be-
cause they can dramatically affect the time needed to download a doc-
ument and even may break certain browsers if they are too large. We
offer more advice on using images effectively in your documents later in
this chapter.
XHTML Basic also supports more general object embedding in mobile
content with the <object> and <param> tags. While the intent is noble,
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