how to add NicEdit textarea Scroll bar?

I am using NicEdit editor in my application but when i am writing text in the text area it is increasing the size instead of adding scrollbar to textarea . Please help with solution how can i add scrollbar to nicEdit editor text area Scrollbar .

set height according to you

<style>
    .nicEdit-main {
        overflow: auto !important;
        height: 5.5em;
    }
</style>