... Block-level elements start on a new line, for example, <H1> and <P> are block-level elements, but <EM> is not. ... Setting Margins or Width . Setting Border Widths, Color, and Style . ... You can also set the width of a block-level element, either to a specific value or to a percentage of the width of the document (or parent element). ... You can set the width of the border surrounding a block-level element by specifying the following properties (shown as CSS syntax/JavaScript syntax values): . ...