why dropdown and multiselectdropdown is not rendering properly in IE 11?

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ASP.NET

C#3.5

IE11

Why dropdown and multiselectdropdown is not rendering properly in IE 11?

I am working in Asp.net with C#3.5.I have issue with multiselectdropdown whose border is rendering with black color and dropdown list whose arrow is going away on selecting the options from the same in IE 11. But in IE 8 all works fine.

Below are the styles used for dropdownlist and multiselect dropdown

.C3_DROPDWNLIST
{
    FONT-WEIGHT: normal;
    FONT-SIZE: 8pt;
    COLOR: black;
    FONT-FAMILY: Verdana,Tahoma, 'MS Sans Serif';
    HEIGHT:20px;
    WIDTH:180px;
    border-width:1px;border-style:solid;
}

<uc1:multiselectdropdown ID="mddlNONMOLStatus" runat="server" ListWidth="350" CssClass="C3_DROPDWNLIST" Style="position: static"
                                                    AutoPostBack="false"></uc1:multiselectdropdown>

<asp:DropDownList ID="drdCorporateId" runat="server" CssClass="C3_DROPDWNLIST" Style="position: static"
                                                                Width="220px">
                                                            </asp:DropDownList

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