MediaWiki:Common.css

/* CSS placed here will be applied to all skins */
<style>
.infobox {
    float: right;
    padding: 5px;
    margin-left: 3px;
    background: #eaecf0;
    border: 3px solid #003aff;
    width: 25%;
}

.infobox th {
    text-align: left;
}
</style>