When you drag an object around the page, blue lines appear to help you center and align objects. You can change the appearance and behavior of these alignment guides.
Choose iWeb > Preferences, and then do one or more of the following:
To change the color, click the Alignment Guides color well and select a color in the Colors window.
To change where the guides appear in relation to objects you’re moving (at the center or the edge of objects), select or deselect the checkboxes.
To turn off alignment guides, deselect both checkboxes.
You can temporarily turn off alignment guides while you’re working on a webpage. Simply hold down the Command key while you drag an object.