MediaWiki:Common.css

/* CSS placed here will be applied to all skins */
.infobox {
    background: #eee;
    border: 1px solid #aaa;
    float: right;
    margin: 0 0 0.5em 0.5em;
    padding: 1em;
    width: 270px;
}
.infobox-title {
    font-size: 1.8em;
    text-align: center;
    vertical-align: top;
}
.infobox-image {
    text-align: center;
}
.infobox-table th {
    text-align: left;
    vertical-align: top;
    width: 40%;
    font-size: 0.80em;
}
.infobox-table td {
    vertical-align: top;
    width: 60%;
    font-size: 0.90em;
}

img[alt]:hover::after {
    content: attr(alt);
    display: block;
    position: absolute;
    background: white;
    padding: 5px;
    border: 1px solid black;
}