Template:Styles/endowment.css

/* To be used with addStyle parameter. Replaces WMF logo with Endowment logo. */

html body .mw-wiki-logo {
    background-image: url('//upload.wikimedia.org/wikipedia/donate/8/85/Wikimedia_Endowment_2x.png') !important;
    background-size: 135px auto !important; /* Needed for mobile */
}