IMP TOPIC

 [1] FULL LENGTH DROP DOWN LIATS 

<asp:DropDownList ID="ddlStudentType" runat="server"
CssClass="fullDropdown">
<asp:ListItem Text="Indian Student" Value="Indian"></asp:ListItem>
<asp:ListItem Text="International Student" Value="International"></asp:ListItem>
</asp:DropDownList>

CSS  CREATE 

.fullDropdown {
width: 100%;
height: 38px;
padding: 6px 12px;
border: 1px solid #ced4da;
border-radius: 4px;
box-sizing: border-box;
}