I'm using flexbox in my modal window. But it doesn't vertically center.

```
.menu-wrapper {
 display: flex;  
align-items: center; 
justify-content: center;
align-content: center;       
}
 .menu-window {
display: flex;
background:white;
margin: auto;
}

```

[Example](https://jsfiddle.net/TsarS/rponj88t/)