如何设置单选按钮颜色

Question

我正在尝试更改单选按钮颜色，同时保持我的绑定。请问我该怎么做？

我尝试了两种方法，将css内联设置为样式表。两者都没有效果。

<div class="col-sm-6">
    <div class="form-group">
        <div >
            <label>@Html.RadioButtonFor(m => m.SelectedGroup, "Red", htmlAttributes: new { @class = "btn-red" }) Number of spots available @Model.Red</label>
        </div>
    </div>
    <div class="form-group">
        <div >
            <label>@Html.RadioButtonFor(m => m.SelectedGroup, "Yellow", new { @style = "color:Yellow;" }) Number of spots available @Model.Yellow</label>
        </div>
    </div>
    <div class="form-group">
        <div >
            <label>@Html.RadioButtonFor( m => m.SelectedGroup, "Green", new { @style = "color:Green;" }) Number of spots available @Model.Green</label>
        </div>
    </div>
</div>

https://codepen.io/anon/pen/vddyax

我试图让它看起来像这样