HTML and CSS Reference
In-Depth Information
he
align
attribute when used in block elements speciies whether the text
of the element should be aligned with the let or right margin, or centered
within the containing element. his is similar to how the CSS
text-align
property is used. However, when the
align
attribute is used in an image
(img)
or table
(table)
element with a value of
left
or
right
, it acts like the CSS
loat
property. It causes the content following the image or table to wrap around the
element on the right or let, respectively.
Sometimes, it is necessary to stop wrapping content around a loated ele-
ment before all of the available space is used. he
clear
attribute does this.
he valid values for the clear attribute are
left
,
right
, and
both
. Adding this
attribute to an HTML element causes the browser to add enough vertical white
space before rendering the element to clear it from any loating element. It
aligns normally with the let or right margin of the containing element. he
clear
attribute works the same way as the
clear
CSS property. he following
two statements have the same efect:
<h3 clear="left">
A heading for this section
</h3>
<h3 style="clear:left">
A heading for this section
</h3>
he second level-three heading is the preferred usage because CSS is more
lexible. For example, if a page had many such level-three heading elements,
instead of adding the
clear
attribute to each, the web author could just add a
class
attribute to accomplish the same thing using CSS. An example would be
<h3 class="clearloat">...</h3>
. he CSS statement to clear all
h3
elements in
the
clearloat
class would go in a
style
element in the document head, along
with any other styling needed for the headings:
<style type="text/css">
h3.clearfloat {
clear: left;
margin-top: 1.5em; /*
provide extra space before each heading
*/
}
</style>
HTML block elements can have
width
and
height
attributes. If the value of
one of these attributes is a positive integer, it speciies the element's width or
height in pixels. A number followed by the percent sign (%) speciies a width