Minimum and maximum value of z-index?

Sachin_Gaur_2572740 0
Viewed 437119

I have a div in my HTML page. I am showing this div based on some condition, but the div is displaying behind the HTML element where I pointed the mouse cursor.

I have tried all values for z-index from 0 - 999999. Can anyone tell me why this is happening?

Is there any minimum or maximum value of Z-INDEX property of CSS?

.divClass {
     position: absolute; 
     left: 25px; 
     top: 25px; 
     width: 320px;
     height: 300px; 
     z-index: 1000; 
}
<table cellspacing="0" cellpadding="0" width="100%">
  <tr>
    <td>
      <asp:HyperLink ID="lnkProgram" runat="server"></asp:HyperLink>
    </td>
  </tr>
  <tr>
     <td>
         <div class="divClass">
           Some Data
         </div>
     </td>
  </tr> 
</table>

I am showing and hiding the div with .divClass onclick via the <asp:hyperlink> using jQuery.

z-index css html
11 Answers

http://www.w3.org/TR/CSS21/visuren.html#z-index

'z-index'

Value: auto | <integer> | inherit

http://www.w3.org/TR/CSS21/syndata.html#numbers

Some value types may have integer values (denoted by <integer>) or real number values (denoted by <number>). Real numbers and integers are specified in decimal notation only. An <integer> consists of one or more digits "0" to "9". A <number> can either be an <integer>, or it can be zero or more digits followed by a dot (.) followed by one or more digits. Both integers and real numbers may be preceded by a "-" or "+" to indicate the sign. -0 is equivalent to 0 and is not a negative number.

Note that many properties that allow an integer or real number as a value actually restrict the value to some range, often to a non-negative value.

So basically there are no limitations for z-index value in the CSS standard, but I guess most browsers limit it to signed 32-bit values (−2147483648 to +2147483647) in practice (64 would be a little off the top, and it doesn't make sense to use anything less than 32 bits these days)

user_89540

My tests show that z-index: 2147483647 is the maximum value, tested on FF 3.0.1 for OS X. I discovered a integer overflow bug: if you type z-index: 2147483648 (which is 2147483647 + 1) the element just goes behind all other elements. At least the browser doesn't crash.

And the lesson to learn is that you should beware of entering too large values for the z-index property because they wrap around.

Ran_102720

Z-Index only works for elements that have position: relative; or position: absolute; applied to them. If that's not the problem we'll need to see an example page to be more helpful.

EDIT: The good doctor has already put the fullest explanation but the quick version is that the minimum is 0 because it can't be a negative number and the maximum - well, you'll never really need to go above 10 for most designs.

sanchothefat_421470

Conclusion Maximum z-index value is 2,147,483,647 and more than this convert to 2,147,483,647

‌Browser Maximum More Than Maximum
Chrome >= 29 2,147,483,647 2,147,483,647
Opera >= 9 2,147,483,647 2,147,483,647
IE >= 6 2,147,483,647 2,147,483,647
Safari >= 4 2,147,483,647 2,147,483,647
Safari = 3 16,777,271 16,777,271
Firefox >= 4 2,147,483,647 2,147,483,647
Firefox = 3 2,147,483,647 0
Firefox = 2 2,147,483,647 Bug: tag hidden

All Values tested in BrowserStack.

user_32434880

There exist super easy way to write maximal and minimal value for z-index using calc().

Maximal value:

#some-id {
  z-index: calc(9e999)
}

Minimal value:

#some-id {
  z-index: calc(-9e999)
}

calc() Browser compatibility (<number> value support)

  • Firefox - 48+
  • Safari - 7+
  • IE - 9+
  • Opera - 18+
  • Chrome - 31+
  • Edge - 12+
user_177991250
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