jellyfin-jellyfin-1/Jellyfin.Server/wwwroot/api-docs/swagger/custom.css

/* logo */
.topbar-wrapper img[alt="Swagger UI"], .topbar-wrapper span {
    visibility: collapse;
}

.topbar-wrapper .link:after {
    content: '';
    display: block;
    background-image: url(../jellyfin.svg);
    background-position: center;
    background-repeat: no-repeat;
    background-size: contain;
    box-sizing: border-box;
    width: 220px;
    height: 40px;
}
/* end logo */