%@page language="C#"%>
%@import namespace="System.Data"%>
script language="c#" runat="server">
public void page_load(Object obj,EventArgs e)
{
  //创建服务器端控件.
  //指定的标记"LINK"初始化此类的新实例.
  HtmlGenericControl objLink=new HtmlGenericControl("LINK");
  objLink.ID=ID;
  objLink.Attributes["rel"]="stylesheet";
  objLink.Attributes["type"]="text/css";
  objLink.Attributes["href"]="portal.css";
  //此控件不产生任何可见输出,仅作为其他控件的容器,可在其中添加,插入或移除控件.
  MyCSS.Controls.Add(objLink);
}
/script>
html>
head>
    title>c#/title>
asp:placeholder id="MyCSS" runat="server">/asp:placeholder>
/head>
body bgColor="#ffcc66" style="FONT:9pt">
form runat="server">
/form>
/body>
/html>

public void page_load(Object obj,EventArgs e)
{
   if(!Page.IsPostBack){
        //为页面的所有控件设置样式.
        SetCSS(Page.Controls);
   }
}
 private void SetCSS(System.Web.UI.ControlCollection vControls)
 {
     for(int i=0;ivControls.Count;i++)
     { 
        System.Web.UI.Control vControl=vControls[i];
        //得到控件的类型
        //可增加控件类型及相应处理方法
        string PType=vControl.GetType().Name;
        switch (PType)
        {
            case "TextBox":
               TextBox_CSS ((TextBox) vControl);
               break;
            case "Button":
               //Button_CSS ((Button) vControl);
               break;
            case "DataGrid":
               //DataGrid_CSS ((DataGrid) vControl);
               break;
        }
        if(vControl.Controls.Count>0)
            SetCSS(vControl.Controls);
     }
}
private void TextBox_CSS(TextBox tb){
   tb.CssClass="TextBox_show";    
}
form runat="server">
asp:textbox id="Search1" runat="server"/>
asp:textbox id="Search2" CssClass="INPUT" runat="server"/>
/form>