<svg xmlns="http://www.w3.org/2000/svg"
     xmlns:h="http://www.w3.org/1999/xhtml"
     xmlns:xlink="http://www.w3.org/1999/xlink"
     width="300" height="200" viewBox="0 0 300 200">
  <metadata>
    <h:link rel="help" href="https://w3c.github.io/svgwg/svg2-draft/render.html#ZIndexProperty"/>
    <h:link rel="match" href="z-index-ref.svg"/>
    <h:meta name="assert" content="The z-index property allows an element to be assigned to a stack level."/>
  </metadata>

  <rect x="74" y="35" width="70" height="70" fill="red" style="z-index: 1;" />
  <rect x="130" y="50" width="70" height="70" fill="green" />
  <rect x="100" y="80" width="70" height="70" fill="blue" />

</svg>