body {
    background: #fefefe;

    font-family: Sans-Serif;

    line-height: 1.5;
}

header {
    padding: 1em;
    padding-bottom: 4em;

    text-align: center;

    color: #333;
    border-bottom: 0.1em solid #bbb;

    background-image: url(../images/bgnoise_lg.png);
}

header .description {
    color: #888;
}

article {
    margin-left: auto;
    margin-right: auto;

    max-width: 768px;
}

article section {
    margin-bottom: 2em;
}

article h2 {
    margin-top: 2em;
}

textarea {
    width: 100%;
}

pre {
    background: #fafefe;
    padding: 0.5em;
}

article .description {
    margin: 1em;
    padding: 1em;

    max-width: 60em;

    background: #fafafa;

    border: 0.1em solid #eee;
}

article .description h2 {
    margin: 0.83em 0;
}

table {
    width: 100%;
}

.demonstration tfoot {
    background: #fafafa;
}

.controls {
    overflow: auto;
}
.per-page-container {
    margin: 1em;

    float: left;
}
.search-container {
    margin: 1em;

    float: right;
}

body {
    background: #fefefe;

    font-family: Sans-Serif;

    line-height: 1.5;
}

header {
    padding: 1em;
    padding-bottom: 4em;

    text-align: center;

    color: #333;
    border-bottom: 0.1em solid #bbb;

    background-image: url(../images/bgnoise_lg.png);
}

header .description {
    color: #888;
}

article {
    display: block !important;

    margin-left: auto;
    margin-right: auto;

    max-width: 768px;
}

article section {
    margin-bottom: 2em;
}

article h2 {
    margin-top: 2em;
}

textarea {
    width: 100%;
}

pre {
    background: #fafefe;
    padding: 0.5em;
}

article .description {
    margin: 1em;
    padding: 1em;

    max-width: 60em;

    background: #fafafa;

    border: 0.1em solid #eee;
}

article .description h2 {
    margin: 0.83em 0;
}

table {
    width: 100%;
}

.demonstration tfoot {
    background: #fafafa;
}

.controls {
    overflow: auto;
}
.per-page-container {
    margin: 1em;

    float: left;
}
.search-container {
    margin: 1em;

    float: right;
}

Fix centering in demo at Firefox
Fix centering in demo at Firefox
