ng-zorro-antd/dropdown/style/patch.less

An enterprise-class UI components based on Ant Design and Angular

.ant-dropdown-menu {
  & > ul {
    list-style: inherit;
    margin: 0;
    padding: 0;
  }
}

.ant-dropdown {
  top: 0;
  left: 0;
  position: relative;
  width: 100%;
  margin-top: 6px;
  margin-bottom: 6px;
}