IE7 Z-Index Layering Issues

Question

I've isolated a little test case of IE7's z-index bug, but don't know how to fix it. I have been playing with z-index all day long.

What is wrong with z-index in IE7?

Test CSS:

input {
    border: 1px solid #000;
}

div {
    border: 1px solid #00f;
}

ul {
    border: 1px solid #f00;
    background-color: #f00;
    list-style-type: none;
    margin: 0;
    padding-left: 0;
    z-index: 1000;
}

li {
    color: #fff;
    list-style-type: none;
    padding-left: 0;
    margin-left: 0;
}

span.envelope {
    position: relative;
}

span.envelope ul {
    position: absolute;
    top: 20px;
    left: 0;
    width: 150px;
}

Test HTML:

<form>
  <label>Input #1:</label>
  <span id="envelope-1" class="envelope">
    <input name="my-input-1" id="my-input-1" />
      <ul>
        <li>item</li>
        <li>item</li>
        <li>item</li>
        <li>item</li>
      </ul>
  </span>
  <br><br>
  <label>Input #2:</label>
  <span id="envelope-2" class="envelope">
    <input name="my-input-2" id="my-input-2" />
  </span>
</form>

Answer 1

“In IE positioned elements generate a new stacking context, starting with a z-index value of 0. Therefore z-index doesn’t work correctly”.

Try give the parent element a higher z-index value (can be even higher than the child’s z-index value itself) to fix the bug.

Answer 2

This bug seems to be somewhat of a separate issue than the standard separate stacking context IE bug. I had a similar issue with multiple stacked inputs (essentially a table with an autocompleter in each row). The only solution I found was to give each cell a decreasing z-index value.

Answer 3

http://www.vancelucas.com/blog/fixing-ie7-z-index-issues-with-jquery/

$(function() {
var zIndexNumber = 1000;
$('div').each(function() {
    $(this).css('zIndex', zIndexNumber);
    zIndexNumber -= 10;
});
});

Answer 4

If you wanna create dropdown menu and having a problem with z-index, you can solve it by creating z-indexes of same value (z-index:999; for example).. Just put z-index in parent and child div's and that will solve problem. I solve the problem with that. If i put different z-indexes, sure, it will show my child div over my parent div, but, once i want to move my mouse from menu tab to the sub-menu div (dropdown list), it dissapear... then i put z-indexes of same value and solve the problem..

Answer 5

I encountered this issue, but on a large project where HTML changes had to be requested and became a whole issue, so I was looking for a pure css solution.

By placing position:relative; z-index:-1 on my main body content my header drop down content suddenly displayed above the body content in ie7 (it was already displaying without issue in all other browsers and in ie8+)

The problem with that was then this disabled all hover and click actions on all content in the element with the z-index:-1 so i went to the parent element of the whole page and gave it a position:relative; z-index:1

Which fixed the issue and retained the correct layering functionality.

Feels a bit hacky, but worked as required.

Answer 6

I found that I had to place a special z-index designation on div in a ie7 specific styelsheet:

div { z-index:10; }

For the z-index of unrelated divs, such as a nav, to show above the slider. I could not simply add a z-index to the slider div itself.