Question

I can’t center vertically popup_interstitial_table that contains an ads type container.

The fiddle it is autoexplained: http://jsfiddle.net/NomikOS/D8LLM/

jQuery solutions are welcome too.

HTML:

<div id="popup_interstitial">
    <div id="parent">
        <div id="popup_interstitial_pro_head_text">
            Headline text 
        </div>
        <div id="child">
            <div id="popup_interstitial_table">
                <div id="popup_interstitial_row2">
                    <div id="popup_interstitial_title"><?php echo $title; ?></div>
                    <img id="popup_interstitial_image" src="<?php echo $image; ?>">
                    <div id="popup_interstitial_description"><?php echo $description; ?></div>
                </div>
            </div>
        </div>
    </div>
</div>

The related CSS code is:

#popup_interstitial_pro_head_text{
    color:#FFF; 
    font-size: 2em;
    font-weight: normal;
    text-shadow: 0.05em 0.05em #666;
    background-color: #A5CF4C;
    width: 100%;
    padding-left: 1%;
    padding-top: 0.8%;
    padding-bottom: 0.8%;
    border-top-width: thin;
    border-top-style: solid;
    border-top-color: #648323;
    border-bottom-width: thin;
    border-bottom-style: solid;
    border-bottom-color: #759928;
    margin-bottom: 2%;
    -webkit-box-shadow: 1px 1px 8px #333333;
    -moz-box-shadow: 1px 1px 8px #333333;
    khtml-box-shadow: 1px 1px 8px #333333;
    filter: shadow(color=#333333, direction=135, strength=0);
}
#popup_interstitial {
    display: none;
    width: 100%;
    height: 100%;
    position: fixed;
    background-color:#FFFFFF;
    color:#111;
    z-index:9999;
    top:0;
    left:0;
}
#popup_interstitial_table {
    width: 50%;
    margin: 0 auto 0 auto;
    background-color:#E7E7E7;
    padding: 1em 2.2em;
    font: 0.85em "Trebuchet MS", Arial, Helvetica, sans-serif;
    margin-top: 5%;
    vertical-align: center;

}
#popup_interstitial_title{
    color:#FFF; 
    font-size: 1.5em;
    font-weight: bold;
    padding: 0 0 0 0.3em;
    border-bottom-width: thin;
    border-bottom-style: solid;
    border-bottom-color: #777;
    background-color: #888; 
    border-radius: 0.3em;
}
#popup_interstitial_description{
    padding-top: 1.7em;
    padding-bottom: 1.2em;
    border-bottom-width: thin;
    border-bottom-style: solid;
    border-bottom-color: #ccc;
    line-height:1.5em;
}

#popup_interstitial_image{
    vertical-align: baseline;
    margin: 25px 20px 3px 0;
    -webkit-box-shadow: 1px 1px 8px #333333;
    -moz-box-shadow: 1px 1px 8px #333333;
    khtml-box-shadow: 1px 1px 8px #333333;
    filter: shadow(color=#333333, direction=135, strength=0);
    padding: 4px;
    margin-left: 6px;
    float: left;
}

This is the most important:

#parent {position: relative;}
#child {
    padding: 0% 0;
    margin: 0 auto; 
}

Answer 1

To your current structure, you have two solutions to make it work:

1) CSS

Wrap the elements with a div and use this trick:

See this working Fiddle Example! ^{(If you move the frame up and down, you see that the target stays vertically centered.)}

#childWrap {                  // the new element, the mentioned wrapper
  display: table;
  width: 100%;
  height: 100%;
}
#child {                      // your element that needs to be restyled
  display: table-cell;
  width: 100%;
  height: 100%;
  vertical-align: middle;
}
#popup_interstitial_table {   // the element vertically aligned
  width: 50%;
  margin: -48px auto 0 auto;
}

What is done here is to set the wrapper element to display as a table, occupying the entire width and height of its parent (#parent).

Then, we can set the #child to display as a table-cell, and set its contents to vertical align at the middle.

Now the trick, since the #parent also contains another element that you need to stay put, but have its height removed from the “center” calculations for the #popup_interstitial_table, we need to pull the #popup_interstitial_table with a margin-top:-60px to fix its position. The negative margin is the height that the #popup_interstitial_pro_head_text occupies.

Important note:

Since you have this structure, in order to pass to the browser the fix, your #popup_interstitial_pro_head_text needs to work with a single unit, I’ve chosen px for the example.

You had a mixture of % and em on several declarations!

---

On a side note:

Vertical-align: center;

You use:

vertical-align: middle;

See this link for further information!

---

2) JQUERY

With jQuery, you can collect the space being occupied by the #popup_interstitial_table and calculate the necessary top and left fix values to keep it vertically centered:

See this working Fiddle Example! ^{(If you move the frame up and down, you see that the target stays vertically centered.)}

JQUERY

function center() {
  var $target = $('#popup_interstitial_table'),
      $header = $('#popup_interstitial_pro_head_text'),
      fixTop  = ($target.outerHeight(true)/2)-($header.outerHeight(true)/2),
      fixLeft = $target.outerWidth(true)/2;

  $target.css({
    "margin-top": "-" + fixTop + "px",
    "margin-left" : "-" + fixLeft + "px"
  });
}

$(document).ready(function() {
  center();
});

CSS

To prevent massive script calculations, the CSS should get fixed to this:

#parent {
  position: relative;
  height: 100%;        // this was added
}
#child {
  padding: 0% 0;
  height: 100%;        // this was added
}
#popup_interstitial_table {
  width: 50%;
  margin: 0 auto 0 auto;
  background-color:#E7E7E7;
  padding: 1em 2.2em;
  font: 0.85em "Trebuchet MS", Arial, Helvetica, sans-serif;
  position: absolute;  // this was added
  top: 50%;            // this was added
  left: 50%;           // this was added
}

So, a repeat that without changing your current structure, this are the two solutions I could think of to center your element!