bpmn-js-properties-panel/styles/listeners.less

.cam-add-listener {
  > .action-button {
    position: relative;
    margin-left: 10px;
  }
}

[data-list-entry-container] > .bpp-listener-area {
  border: 1px solid @bpp-color-cccccc;
  margin: 10px 1px;
  padding: 10px;
}

.bpp-listener-area {
  position: relative;
  > .action-button {
    position: absolute;
    right: 0;
    top: 0;
    border: none;
    background: none;
  }
}

.bpp-listener-area + .bpp-listener-area {
  margin-top: 20px;
}