The following styles are applied here:
html {
margin: 2em;
border: 2em solid red;
padding: 1em;
background: aqua;
}
body {
margin: 1em;
border: 2em solid green;
padding: 2em;
background: yellow;
color: black;
}
Around the edges of this page, you should see 2em of aqua (thanks to the statement in CSS2 14.2 that "The background of the box generated by the root element covers the entire canvas."), 2em of red, 2em of aqua, 2em of green, 2em of yellow, and then this black text on the yellow background. If the document doesn't fill the viewport, the aqua at the bottom (below the red) should be bigger.
(Back to CSS Testing Information, David Baron)