The Positioning style attributes change the tag or block of selected text into a new layer using the default tag for defining layers as defined by the Layer preferences. (See also Layer preferences.) Unless you've changed this setting, Dreamweaver uses the DIV tag. See also Style sheets overview and Editing a style.

To open the Style Definition dialog box, Choose Window > Styles and click Edit Style Sheet. In the dialog box that appears, choose a style and click Edit. Click the panel names on the left side of the dialog box. Leave any of the following attributes empty if they are not important to the style:

Type determines how the browser should position the layer as follows:

	Absolute places the layer using the coordinate entered in the Placement boxes relative to the top left corner of the page.
	Relative places the layer using the coordinates entered in the Placement boxes relative to object's position in the text flow of the document. This option does not display in the Document window.
	Static places the layer at its location in the text flow.

Visibility determines the following initial display condition of the layer. (Use the visibility property in a scripting environment, such as JavaScript, to display layer contents dynamically.) If you do not specify a visibility property, the default behavior on most browsers is to inherit the parent's value.

	Inherit inherits the visibility property of the layer's parent.
	Visible displays the layer contents, regardless of the parent's value.
	Hidden hides the layer contents, regardless of the parent's value.

Z-Index determines the stacking order of the layer. Higher numbered layers appear above lower numbered layers. Values can be positive or negative. It's easier to change the stacking order of layers using the Layers palette. See Changing the stacking order of layers.

Overflow (CSS layers only) determines what happens if the contents of a layer exceed its size, as follows:

	Visible increases the layer size so that all of its contents are visible. The layer expands down and to the right.
	Hidden maintains the layer's size and clips any content that doesn't fit. No scroll bars are provided.
	Scroll adds scroll bars to the layer whether or not the contents exceed the layer's size. Specifically providing scroll bars avoids problems with them appearing and disappearing in a dynamic environment. This option does not display in the Document window and works only in browsers that support scroll bars.
	Auto makes scroll bars appear only when the layer's contents exceed its boundaries. This option does not display in the Document window.

Placement specifies the location and size of the layer. How the browser interprets the location depends on the setting for Type. Size values are overridden if the content of the layer exceeds the specified size.

For CSS layers, the default values for location and size are in pixels. Other valid units can be specified by entering the following unit abbreviations: pc (picas), pt (points), in (inches), mm (millimeters), cm (centimeters), or % (percentage of the parent's value). The abbreviations must follow the value without a space, for example, 3mm.

Clip defines the part of the layer that is visible. By specifying a clipping region, you can access it with a scripting language, such as JavaScript, and manipulate the properties to create special effects such as wipes.