[comp:menu] vertical 模式下，dark 主题会有白色阴影，

[danranVm]

• I have searched the issues of this repository and believe that this is not a duplicate.

Reproduction link

components-menu-demo-StateSwitching

Steps to reproduce

• 选择 dark 主题
• 展开任意子菜单

What is expected?

样式正常

What is actually happening?

Environment Info

    @idux/cdk: ^1.0.0-beta.19 => 1.0.0-beta.19 
    @idux/components: ^1.0.0-beta.19 => 1.0.0-beta.19 
    @idux/pro: ^1.0.0-beta.19 => 1.0.0-beta.19 
    vue: ^3.2.33 => 3.2.3

[idux-bot]

Translation of this issue:

[Comp: Menu] Under the vertical mode, the Dark theme will have white shadows.

• I have searched the [issues] (https://github.com/iduxfe/idux/isSues) of this repository that this is not a duplicate.

REPRODUCTION LINK

[components-manu-demo-stateswitching] (https://idux.site/components/zh#componu-demo-Stateswitching)

STEPS To Reproduce

-Cose Dark theme
-Ended Renfu Sub -menu

What is exfected?

Normal

What is actually happy?

! [Image] (https://user-images.githubusercontent.com/25052421/178704579- Eff3a984-C7BF-42F6-A24b207a840b.png))

ENVIRONMENT Info

    @idux/cdk: ^1.0.0-beta.19 => 1.0.0-beta.19 
    @idux/components: ^1.0.0-beta.19 => 1.0.0-beta.19 
    @idux/pro: ^1.0.0-beta.19 => 1.0.0-beta.19 
    vue: ^3.2.33 => 3.2.3