<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">

 <head>

  <title>CSS Writing Modes Test: 'vertical-lr' and margin collapsing - left margin of a block collapses with left margin of its first child</title>

  <link rel="author" title="Gérard Talbot" href="http://www.gtalbot.org/BrowserBugsSection/css21testsuite/" />
  <link rel="help" href="http://www.w3.org/TR/css-writing-modes-3/#logical-direction-layout" title="7.4 Flow-Relative Mappings" />
  <link rel="match" href="../reference/ref-filled-green-100px-square.xht" />

  <!--
  Test adapted from
  http://test.csswg.org/suites/css2.1/nightly-unstable/html4/margin-collapse-017.htm

  "
  The margin collapsing rules apply exactly with the block-start margin substituted for the top margin and the block-end margin substituted for the bottom margin.
  "
  -->

  <meta content="ahem image" name="flags" />
  <meta name="assert" content="This test checks that, in a vertical-lr context, the left margin an in-flow block element collapses with its first in-flow block-level child's left margin if the element has no top border, no top padding, and the child has no clearance." />

  <link rel="stylesheet" type="text/css" href="/fonts/ahem.css" />
  <style type="text/css"><![CDATA[
  div
    {
      font: 25px/1em Ahem;
      height: 4em;
    }

  div#wrapper
    {
      background: red url("support/margin-collapse-2em-space-wm-vert.png") -1em top;
      border-left: green solid 1em;
      width: 3em;
      writing-mode: vertical-lr;
    }

  div#parent
    {
      margin-left: 2em; /* block-start margin */
    }

  div#first-child
    {
      background-color: green;
      margin-left: 2em; /* block-start margin of child */
      width: 1em;
    }
  ]]></style>

 </head>

 <body>

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

  <div id="wrapper">
    <div id="parent">
      <div id="first-child"></div>
    </div>
  </div>

 </body>
</html>