gnu-social/public/plugins/Embed/css/embed.css

.u-photo.oembed {
    float: left;
    margin-bottom: 1ex;
    margin-right: 1em;
}

.p-author.oembed {
    font-style: italic;
}

.p-summary.oembed {
    line-height: 1.25em;
    max-height: 5em;
    overflow: auto;
}