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      <base href="https://bugs.webkit.org/" />
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    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - matchMedia late by 1px compared to CSS media query"
   href="https://bugs.webkit.org/show_bug.cgi?id=158422">158422</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>matchMedia late by 1px compared to CSS media query
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>WebKit
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>Safari 9
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>Unspecified
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Unspecified
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>Normal
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P2
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>WebCore JavaScript
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>webkit-unassigned&#64;lists.webkit.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>yeldinov&#64;gmail.com
          </td>
        </tr></table>
      <p>
        <div>
        <pre>&#64;media (min-width: 720px) and (max-width: 989px) {
    #css {
        background-color: orange;
    }
}

window.matchMedia('(min-width: 720px) and (max-width: 989px)').addListener( ... );

At 720px background color will become orange, and only at 721px MediaQueryList will fire an event notifying that breakpoint changed</pre>
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          <li>You are the assignee for the bug.</li>
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