css/css-backgrounds/box-shadow-029.html

<!DOCTYPE html>

  <meta charset="UTF-8">


  <title>CSS Backgrounds Test: box-shadow and empty box (edge)</title>

  <link rel="author" title="Gérard Talbot" href="http://www.gtalbot.org/BrowserBugsSection/css21testsuite/">
  <link rel="help" href="https://www.w3.org/TR/css-backgrounds-3/#the-box-shadow">
  <link rel="match" href="../reference/ref-filled-green-100px-square.xht">

  <meta content="This test checks that an empty box can have a box shadow." name="assert">

  <!--

  <shadow> = inset? && <length>{2,4} && <color>?

  A comma-separated pair of numbers in curly braces {A,B}
  indicates that the preceding type, word, or group occurs
  at least A and at most B times.

  A question mark (?) indicates that the preceding type,
  word, or group is optional (occurs zero or one times).

  The components of each <shadow> are interpreted as follows:

  1st <length>
    Specifies the horizontal offset
    of the shadow. A positive value draws a shadow that is offset to the right of the box, a negative length to the left.
  2nd <length>
    Specifies the vertical offset
    of the shadow. A positive value offsets the shadow down, a negative one up.
  4th <length>
    Specifies the spread distance. Positive values cause the shadow to expand in all directions by the specified radius. Negative values cause the shadow to contract.

  -->

  <style>
  div#green-overlapping-test
    {
      background-color: red;
      height: 0px;
      width: 0px;

      box-shadow: green 50px 50px 0px 50px;
    }

  div#red-overlapped-reference
    {
      background-color: red;
      height: 100px;
      position: relative;
      width: 100px;
      z-index: -1;
    }
  </style>

  <p>Test passes if there is a filled green square and <strong>no red</strong>.

  <div id="green-overlapping-test"></div>

  <div id="red-overlapped-reference"></div>