zulip/static/styles/integrations_dev_panel.css

#panel_div {
    margin: auto;
    width: 720px;
    margin-top: 50px;
    border: 3px solid;
    border-color: rgb(0, 128, 0);
    padding: 10px;
}

#fixture_body {
    height: 500px;
    width: 700px;
}

#send_fixture_button {
    float: right;
}

#URL {
    width: 90%;
}

.center-text {
    text-align: center;
}

.pad-top {
    padding-top: 30px;
}