Mouse hover change image position and size

Question

I'm trying to do a button menu for my web site and I have an issue with the position of the image on mouse hover. This is what I have created so far http://jsfiddle.net/tNLUx/

On mouseover, I want the selected image to grow and the other ones keep their same position just like the first image... how do I make the down images to grow and move down instead of moving up?

#btnSocial {
  width:100px;
  position: relative;
  opacity: 0.5;
  -webkit-opacity: 0.5;
  -moz-opacity: 0.5;
  transition: 0.5s ease;
  -webkit-transition: 0.5s ease;
  -moz-transition: 0.5s ease;
}
#btnSocial:hover{
  width: 150px;
  opacity: 1;
  -webkit-opacity: 1;
  -moz-opacity: 1;
}

<img src="http://img24.imageshack.us/img24/3221/32845401.png" alt="img1" id="btnSocial" class="social1" />
<img src="http://img24.imageshack.us/img24/3221/32845401.png" alt="img1" id="btnSocial" class="social2"/>
<img src="http://img24.imageshack.us/img24/3221/32845401.png" alt="img1" id="btnSocial" class="social3"/>
<img src="http://img24.imageshack.us/img24/3221/32845401.png" alt="img1" id="btnSocial" class="social4"/>

Answer 1

Use transform: scale(x, y) to scale the object.
Use transform: translate(x, y) to move the object.
Those two properties can also be combined: transform: scale(x, y) translate(x, y).

Example:

.btn-social {
    width: 100px;
    position: relative;
    opacity: 0.5;
    transition: 0.3s ease;
    cursor: pointer;
}

.btn-social:hover {
    opacity: 1;

    /** default is 1, scale it to 1.5 */
    transform: scale(1.5, 1.5);

    /** translate 50px from left, and 40px from top */
    /** transform: translate(50px, 40px); */

    /** combine both scale and translate */
    /** transform: scale(1.5, 1.5) translate(50px, 40px); */
}

<img src="http://sstatic.net/stackexchange/img/logos/so/so-icon.png?v=c78bd457575a" class="btn-social" />
<img src="http://sstatic.net/stackexchange/img/logos/so/so-icon.png?v=c78bd457575a" class="btn-social" /><br />
<img src="http://sstatic.net/stackexchange/img/logos/so/so-icon.png?v=c78bd457575a" class="btn-social" />
<img src="http://sstatic.net/stackexchange/img/logos/so/so-icon.png?v=c78bd457575a" class="btn-social" />

Answer 2

Check this http://jsfiddle.net/tNLUx/11/

Removed position: relative; from css

#btnSocial{
    width:100px;
    opacity: 0.5;
    -webkit-opacity: 0.5;
    -moz-opacity: 0.5;
    transition: 0.5s ease;
    -webkit-transition: 0.5s ease;
    -moz-transition: 0.5s ease;

}