[html] Make <body> fill entire screen?

If you have a border or padding, then the solution

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html, body {_x000D_
    margin: 0;_x000D_
    height: 100%;_x000D_
}_x000D_
body {_x000D_
    border: solid red 5px;_x000D_
    border-radius: 2em;_x000D_
}
_x000D_
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produces the imperfect rendering

not good

To get it right in the presence of a border or padding

good

use instead

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_x000D_
html, body {_x000D_
    margin: 0;_x000D_
    height: 100%;_x000D_
}_x000D_
body {_x000D_
    box-sizing: border-box;_x000D_
    border: solid red 5px;_x000D_
    border-radius: 2em;_x000D_
}
_x000D_
_x000D_
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as Martin pointed out, although overflow: hidden is not needed.

(2018 - tested with Chrome 69 and IE 11)