Hi,
Make sure the generated shortcode for textarea looks something like this :
[textarea your-message 40×10 “your message here …”]
This should work with the design.
Textarea row height seems overriden by theme CSS preventing it to take actual rows height. So this can be fix by adding simple custom CSS. Follow the steps below:
1. First you need to Go to your Dashboard -> Appearance -> Customize -> Theme Options -> Custom CSS options.
2. In this section you need to add this CSS:
.wpcf7-form-control {
height: auto;
}