vue+iview tabs context-menu 弹出框修改样式的方法

<Tabs type="card" closable class="main-tags-col-tabs" 
      v-model="activeTab" @on-click="handleClickTag" 
:before-remove="handleBeforeRemove" 
capture-focus @on-contextmenu="contextmenu">
        <TabPane
          v-for="(item, index) in tagList"
          :key="index"
          :name="item.name"
          :label="item.label"
          icon="custom iconfont icon-dot-circle"
          :closable="index != 0"
          :context-menu="index == 0 ? false : true"
        ></TabPane>
        <template slot="contextMenu">
          <DropdownItem @click.native="handleCloseTag('closeOther')">
            <Icon type="md-close"></Icon>
            <span class="dropdown-icon-space">关闭其他</span>
          </DropdownItem>
          <DropdownItem @click.native="handleCloseTag('closeAll')">
            <Icon type="ios-close-circle-outline"></Icon>
            <span class="dropdown-icon-space">关闭所有</span>
          </DropdownItem>
        </template>
      </Tabs>

contextmenu(item) {
      this.$nextTick(() => {
        const dropdownMenu = document.querySelector('.ivu-dropdown-transfer')
        console.log(dropdownMenu)
        if (dropdownMenu) {
          dropdownMenu.classList.add('fixed-context-menu')
        }
      })
      this.contextMenuActiveName = item.name
    },

<style>
.fixed-context-menu {
  top: 97px !important;
}
</style>