These are called tag-less styles. Use the background-color attribute in conjunction with the body tag. Alternatively, you can also use the generic background attribute. You may include this attribute along with others affecting the body as well, e.g. text color or font. When I apply a background color to a whole paragraph, it comes out with a jagged right edge rather than an even rectangular block.
Background color matches the element text exactly.
The colored background is not rectangular, but instead follows the margins of the text flow. To even things up within text flows, you'll have to use justified text or fall back on a table to house the effected flow.