主题：为何移动开发应用时，手机端打开网页有时会出现框架CSS失效的现象？目前发现在微信中打开时会出现框架显示不稳定情况。

你确定这段代码，写到httprequest的最顶部了没有？

Dim fl As String = "d:\web\" & e.path
If filesys.FileExists(fl)
    Dim idx As Integer = fl.LastIndexOf(".")
    Dim ext As String  = fl.SubString(idx)
    Select Case ext
        Case ".jpg",".gif",".png",".bmp",".wmf",".js",".css" ,".html",".htm",".zip",".rar"
            e.WriteFile(fl)
            Return '这里必须返回
    End Select
End If