How can I center text inside a div element using CSS

Question

I want to center the text in paragraph elements both vertically and horizontally inside the div elements (red boxes). I'm trying to use vertical-align:middle but it's not working. Any help would be appreciated, Thanks.

http://jsfiddle.net/9NLtB/

.transparent-btn {
    font:bold 20px"Arial Black", Gadget, sans-serif;
    font-style:normal;
    color:#ffd324;
    background-color: rgba(255, 0, 0, .90);
    border:2px solid #000;
    text-shadow:0px -1px 1px #222222;
    box-shadow:0px 0px 12px #2e2300;
    -moz-box-shadow:0px 0px 12px #2e2300;
    -webkit-box-shadow:0px 0px 12px #2e2300;
    border-radius:15px 15px 15px 15px;
    -moz-border-radius:15px 15px 15px 15px;
    -webkit-border-radius:15px 15px 15px 15px;
    width:100px;
    height:100px;
    margin:5px;
    display:inline-block;
    position:relative;
}

.transparent-btn:active {
    cursor:pointer;
    position:relative;
    top:2px;
}

#wrapper {
    text-align:center;
}

p {
    display:inline-block;
    vertical-align:middle;
}

Answer 1

Add a line-height property to your div, then specify it as normal in your text element.

.transparent-btn {
    line-height: 100px;
    text-align: center;
}


span {
    display: inline-block;
    vertical-align: middle;
    line-height: normal;
}

And yes, this works with multiple lines of text:

Demo: http://jsfiddle.net/9NLtB/12/