MediaWiki:Themes.css

/* Portable infobox styling */
.portable-infobox {
    width:300px!important;
    background:transparent;
    border:1px solid #aaa;
}
.portable-infobox .pi-title {
    font-size:15px;
    line-height:140%;
}

.pi-caption {
    line-height:130%
    color:#333;
}