# Stacking Context

# Stacking Context

In this example every positioned element creates its own stacking context, because of their positioning and z-index values. The hierarchy of stacking contexts is organized as follows:

Stacking Context Result

  • Root
      - DIV #1 - DIV #2 - DIV #3 - DIV #4 - DIV #5 - DIV #6

      It is important to note that DIV #4, DIV #5 and DIV #6 are children of DIV #3, so stacking of those elements is completely resolved within DIV#3. Once stacking and rendering within DIV #3 is completed, the whole DIV #3 element is passed for stacking in the root element with respect to its sibling's DIV.

      HTML:

      <div id="div1">
        <h1>Division Element #1</h1>
        <code>position: relative;<br/>
        z-index: 5;</code>
      </div>
      <div id="div2">
        <h1>Division Element #2</h1>
        <code>position: relative;<br/>
        z-index: 2;</code>
      </div>
      <div id="div3">
        <div id="div4">
          <h1>Division Element #4</h1>
          <code>position: relative;<br/>
          z-index: 6;</code>
        </div>
        <h1>Division Element #3</h1>
        <code>position: absolute;<br/>
        z-index: 4;</code>
        <div id="div5">
          <h1>Division Element #5</h1>
          <code>position: relative;<br/>
          z-index: 1;</code>
        </div>
        <div id="div6">
          <h1>Division Element #6</h1>
          <code>position: absolute;<br/>
          z-index: 3;</code>
        </div>
      </div>
      
      

      CSS:

      * {
          margin: 0;
      }
      html {
          padding: 20px;
          font: 12px/20px Arial, sans-serif;
      }
      div {
          opacity: 0.7;
          position: relative;
      }
      h1 {
          font: inherit;
          font-weight: bold;
      }
      #div1,
      #div2 {
          border: 1px dashed #696;
          padding: 10px;
          background-color: #cfc;
      }
      #div1 {
          z-index: 5;
          margin-bottom: 190px;
      }
      #div2 {
          z-index: 2;
      }
      #div3 {
          z-index: 4;
          opacity: 1;
          position: absolute;
          top: 40px;
          left: 180px;
          width: 330px;
          border: 1px dashed #900;
          background-color: #fdd;
          padding: 40px 20px 20px;
      }
      #div4,
      #div5 {
          border: 1px dashed #996;
          background-color: #ffc;
      }
      #div4 {
          z-index: 6;
          margin-bottom: 15px;
          padding: 25px 10px 5px;
      }
      #div5 {
          z-index: 1;
          margin-top: 15px;
          padding: 5px 10px;
      }
      #div6 {
          z-index: 3;
          position: absolute;
          top: 20px;
          left: 180px;
          width: 150px;
          height: 125px;
          border: 1px dashed #009;
          padding-top: 125px;
          background-color: #ddf;
          text-align: center;
      }
      
      

      Result:

      Stacking Context Result

      Source: https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Positioning/Understanding_z_index/The_stacking_context.