Editor button/tools collapse/break in Internet Explorer 11 (IE11)

[nkdweb]

Hi,

Thanks for the Angular WYSIWYG plugin.

Angular WYSIWYG editor is working perfectly in all broswers like Google chrome, firefox etc except Internet explorer 11.

Please refer the screenshot of issues

Plunker page without any modification

Step to reproduce the issue

1. Enter some text in text editor
2. Select the text and click any alignment button, like left justify, center justify & right justify
3. Now the editor button / tools will collapse / break as shown below.

Please suggest the solution for this. Your help is highly appreciated.