How to hide the HTML select up-down arrows on gmail email client? I am able to hide them on Apple mail client.

The up-down arrows are not seen on the chrome and firefox browsers but they are visible on the gmail email client irrespective of the browser. I have been trying since 10 hours but unable to hide them.

I have provided the code below. Please let me know how to solve it. Any kind of help will be greatly appreciated.

<select id="country_code" name="country_code" form="phoneform"
                                  style="-webkit-appearance: none;
                                      -moz-appearance: none;
                                      appearance: none;
                                      -o-appearance: none;

                                      text-indent: 15px;
                                      text-align: justify;
                                      text-overflow: clip;
                                      border-radius: 0;
                                      -o-border-radius: 0;
                                      border: 1px solid green;
                                      outline: 1px solid red;
                                      background-image: url(caret-image.png), -webkit-linear-gradient(#FAFAFA, #F4F4F4 100%, #E5E5E5);
                                      background-repeat: no-repeat;
                                      background-size: 8px 6px;
                                      background-position: 5px center;
                                      background-color: white;
                                      color: #555;
                                      font-family: 'OpenSans-Light', 'Open Sans', 'Helvetica Neue', 'Helvetica', 'sans-serif';
                                      font-size: 14px;
                                      margin: 0;
                                      padding: 0;
                                      overflow: visible;
                                      width: 65px;
                                      height: 32px;
                            <option value="1">1</option>
                            <option value="20">20</option>
                            <option value="212">212</option>