input group is not aligned

Question

hey in below code input group is not aligned so, how to fix it?

 

 

<div class="form-group">

<div class="input-group">

<span class="input-group-addon glyphicon glyphicon-envelope"></span>

<asp:TextBox ID="txt_email" CssClass="form-control" runat="server" placeholder="Email" required="required"></asp:TextBox>

</div>

</div>

 

output : https://ibb.co/BzfNkqJ