在想引入的.cs 檔的 <asp:Content ID=”Content1″ ContentPlaceHolderID=”MainContent” runat=”server”>下方加入

<link rel=”stylesheet” href=”Content/CommonStyle.css”>

如下:

<asp:Content ID="Content1" ContentPlaceHolderID="MainContent" runat="server">
      <link rel="stylesheet" href="Content/CommonStyle.css">