Add / Remove CSS class for webforms controls

WebControlExtensions.vb

    Public Module WebControlExtensions
        <Extension>
        Public Function AddClass(control As WebControl, cssClass As String) As WebControl
            Dim cssClasses = control.CssClass.Split(New Char() {" "c}, StringSplitOptions.RemoveEmptyEntries).ToList()
            If Not cssClasses.Contains(cssClass) Then cssClasses.Add(cssClass)
            control.CssClass = String.Join(" ", cssClasses.ToArray())
            Return control
        End Function

        <Extension>
        Public Function RemoveClass(control As WebControl, cssClass As String) As WebControl
            Dim cssClasses = control.CssClass.Split(New Char() {" "c}, StringSplitOptions.RemoveEmptyEntries).ToList()
            cssClasses.RemoveAll(Function(s) s = cssClass)
            control.CssClass = String.Join(" ", cssClasses.ToArray())
            Return control
        End Function
    End Module