How to center the center circle?

Question

How to center the center circle (CSS only)?   [Assume latest CSS3 browser support.]

Must maintain v/h centering when parent w/h changes dynamically.

Would the experimental CSS Box Model spec help here?

Thanks.

http://jsfiddle.net/dragontheory/VdJFa/5/

<div class="parent">
    <div class="middle">
        <div class="circle">
            <div class="circle"></div>
        </div>
    </div>
</div>

.parent         {display: table; 
                margin: 50px auto;
                background: lightgray;
                height: 100px;
                width: 100px;}

.middle         {display: table-cell; 
                vertical-align: middle;}

.circle         {margin: auto;
                border: solid 10px blue;
                border-radius: 50%;
                opacity: 0.3;
                width: 50px;
                height: 50px;}

.circle .circle {width: 15px;
                height: 15px;}

Answer 1

You need to give your middle container, appropriate padding,It will help bringing the content to the center.

You can achieve the same by giving a left i.e. making your .middle as:

.middle {
    vertical-align: middle;
    text-align:center;
    left:10%;
    position:relative; /*makes left effective*/
    display:table-cell;
}

Also, you have to give your child div.circle a specific width and height combined with border-radius to align it and to give it a shape of circle.

And finally you need to play with the margin of the inner circle to align it.

see this fiddle