width of textarea in MVC - html

Question

I use IDE to generate a view and controller from model automatically in MVC, however, when I try to change the size of textAreafor, I found the width has limitation , I cant make it more widely... here is my code, hope for some help
#model VeganCommunityApplication.Models.Article
#{
ViewBag.Title = "Create";
}
<h2>Create</h2>
#using (Html.BeginForm())
{
#Html.AntiForgeryToken()
<div class="form-horizontal">
<h4>Article</h4>
<hr />
#Html.ValidationSummary(true, "", new { #class = "text-danger" })
.
.
.
<div class="form-group">
#Html.LabelFor(model => model.Content, htmlAttributes: new { #class = "control-label col-md-2" })
<div class="col-md-10">
#Html.TextAreaFor(model => model.Content,20,70,new {#style="width:400px;height:400px" })
#Html.ValidationMessageFor(model => model.Content, "", new { #class = "text-danger" })
</div>
</div>
<div class="form-group">
<div class="col-md-offset-2 col-md-10">
<input type="submit" value="Create" class="btn btn-default" />
</div>
</div>
</div>
}
<div>
#Html.ActionLink("Back to List", "Index")
</div>
#section Scripts {
#Scripts.Render("~/bundles/jqueryval")
}

Answer 1

Change your textarea to this:
#Html.TextAreaFor(model => model.Content,20,70,new { #class = "col-md-12" })
This will make it 100% as wide as it's parent element.
For reference: Bootstrap grid system

Answer 2

You can change it like this:
#Html.TextAreaFor(model => model.Content, new { #class = "whatever-class", #cols = 40, #rows = 40 })
.whatever-class{
width:400px;
height:400px
}