Open the developer tools and find the input element in your browser. See if there is a max-width property in the TextArea element. If so, then all you need to do is the following code to overwrite it.
- You can use this code if you bind only one model to your look
@Html.TextArea("NameOfElement", Model.propertyName, new {style = "max-width:100% !important;"})
--- OR ---
--- Use this code, you bind a model from the list of models.
@Html.TextAreaFor(m => m.propertyName, new {style="max-width:100%", @id = "ElementId"})
:
1) , .
2) TextArea - . elementID. TextAreaFor elementID, .