Can the 'stock' mobile nav in Webflow be edited to fill the entire screen and ensure menu items are centered both vertically and horizontally, potentially using a flexbox? The current issue is that when the menu is open, it covers up the close button. Assistance would be greatly appreciated.

Yes, you can edit the 'stock' mobile nav in Webflow to fill the entire screen and center menu items vertically and horizontally using flexbox.

To achieve this, you'll need to follow these steps:

1. Open your Webflow project and go to the page where you want to edit the mobile nav.

2. Select the mobile nav element, either by clicking on it directly in the designer or selecting it from the Navigator panel.

3. In the Styles panel, click on the Flex layout settings (the icon that looks like four rectangles). This will enable flexbox properties for the mobile nav.

4. Set the flex direction to "column" to stack the menu items vertically.

5. Set the justify content property to "center" to center the menu items horizontally.

6. Set the align items property to "center" to center the menu items vertically.

7. To ensure that the mobile nav fills the entire screen, you'll need to adjust its height. You can do this by setting the height property to "100vh". The "vh" unit refers to the viewport height, so this will make the mobile nav fill the entire screen vertically.

8. Finally, to ensure that the close button is visible when the menu is open, you can adjust its position using absolute positioning or by increasing the z-index value.

Here's a CSS example that combines all these steps:

```
.mobile-nav {
display: flex;
flex-direction: column;
justify-content: center;
align-items: center;
height: 100vh;
}

.close-button {
position: absolute;
z-index: 999;
}
```

By applying these styles, you should be able to create a mobile nav that fills the entire screen, centers the menu items both vertically and horizontally, and ensures that the close button is visible when the menu is open.

Remember to adjust the class names and properties according to your specific setup.