Onclick CSS button effect

Question

I'm creating a CSS button and I'm trying to make an onclick effect: when the user clicks on the button it would push down the button text by 1px. My problem here is that it's pushing the whole bottom of the button. How would you proceed?

<div class="one">
    <p><a id="button" href=#>Button</a></p>
</div>

Here's the CSS:

#button {
    display: block;
    width:150px;
    margin:10px auto;
    padding:7px 13px;
    text-align:center;
    background:#a2bb33;
    font-size:20px;
    font-family: 'Arial', sans-serif;
    color:#ffffff;
    white-space: nowrap;
    box-sizing: border-box;
    -webkit-box-sizing: border-box;
    -moz-box-sizing: border-box;

}

#button:active {
    vertical-align: top;
    padding-top: 8px;
}

.one a {
    text-decoration: none;
}

Answer 1

You should apply the following styles:

#button:active {
    vertical-align: top;
    padding: 8px 13px 6px;
}

This will give you the necessary effect, demo here.

Answer 2

Push down the whole button. I suggest this it is looking nice in button.

#button:active {
    position: relative;
    top: 1px;
}

if you only want to push text increase top-padding and decrease bottom padding. You can also use line-height.