The cols attribute

The cols attribute is required by the <multicol> tag to define the number of columns. If omitted, Netscape creates just one column, as if the <multicol> tag isn't there at all. You may create any number of columns, but in practice, more than three or four columns make text unreadable on most displays.

The following example creates a three-column layout:

<h1 align=right>Temperature Effects</h1>
<multicol cols=3>
The effects of cooler weather on the kumquat's ripening process 
vary based upon the temperature.  Temperatures above 28&deg; 
sweeten the fruit, while four or more hours below 28&deg; will
damage the tree.  The savvy quat farmer will carefully monitor 
the temperature, especially in the predawn hours when the 
mercury dips to its lowest point.  Smudge pots and grove heaters
may be required to keep the trees warm; many growers will spray
the trees with water to create an insulating layer of ice over
the fruit and leaves.
<p>
If a disastrous frost is predicted, below 20&deg;, the only 
recourse may be to harvest the fruit early to save it from an
assured disaster.  Kumquats may subsequently be ripened using
any of the popular methane and cyanoacrylate injection systems
used for other citrus fruits.  Used correctly, these systems will 
produce fruit whose taste is indistinguishable from tree-ripened
kumquats.
</multicol>

The results are shown in Figure 6.4.

You can see in Figure 6.4 how Netscape has balanced the columns to approximately equal lengths. You also can see how several lines within the columns appear shorter, since longer words were wrapped to the next line of text. These overly ragged right margins within the columns are unavoidable and serve to emphasize that you shouldn't create more than four or five columns in a flow. Our example is still barely readable if displayed as five columns; it breaks down completely and even induces rendering errors if cols is set to 7, as shown in Figure 6.5.

The gutter attribute

The space between columns is known as the gutter. By default, Netscape creates a gutter 10 pixels wide between each of your columns. To change this, set the gutter attribute's value to the desired width in pixels. Netscape will reserve this much space between your columns; the remaining space will be used for the columns themselves.

Figure 6.6 shows the effect this can have on your columns. In this figure, we've reformatted our sample text using <multicol cols=3 gutter=50>. Contrast this with Figure 6.4, which uses the default 10 pixel gutters.

The width attribute

Normally, the <multicol> tag fills the current width of the current text flow. To have your multiple columns occupy a thinner space, or to extend them beyond the visible window, use the width attribute to specify the overall width of the <multicol> tag. The columns will be resized so that the columns plus the gutters fill the width you've specified.[1] The width may be specified as an absolute number of pixels or as a percentage of the width of the current text flow.

[1] To be exact, each column will be (w-g(n-1))/n pixels wide, where w is the width of the <multicol> tag, g is the width of a gutter, and n is the number of columns. Thus, using <multicol cols=3 gutter=10 width=500> creates columns that are 160 pixels wide.

Figure 6.7 shows the effects of adding width="75%" to our column example, retaining the default gutter width of 10 pixels.

Be careful when you reduce the size of your columns if they include images or other fixed-width elements. Netscape will not wrap text around images that extend beyond the boundaries of a column. Instead, the image simply covers the adjacent columns, ruining your document. Always make sure that embedded elements in columns are small enough to fit within your columns, even on fairly small browser displays.

The style and class attributes

Use the style attribute with the <multicol> tag to create an inline style for all the content inside the tag. The class attribute lets you label the section with a name that refers to a predefined class of the <muticol> tag declared in some document-level or externally defined style sheet. [the section called "Inline Styles: The style Attribute"] [the section called "Style Classes"].