Apply style to HTML Progress element in CSS

how to apply style on file progress bar

i want to apply the css style to progress bar like green and make it gradient

how to do that

please advice

<progress id="fileProgress" class="p-bar" style="display: none"></progress>
<input type="button" class="c-attach" id="btncancel" onclick="myFunction()" value="X" style="display:none" >
<span id="lblMessage"></span>
 <%--<input type="button" id="btnUpload" value="Upload" />--%>
</div>
<label id="lbluploadcontrol" class="file-upload">
    <span class="inbox-attach">
        <asp:Image ID="Image1" runat="server" ImageUrl="~/inbox/attach.png" /></span>    
    <input type="file" name="postedFile" />
</label>