Source/core/css/themeMac.css

/* Copyright 2014 The Chromium Authors. All rights reserved.
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

select, input[type="color"][list] {
    background-color: #f8f8f8;
    border: 1px solid #a6a6a6;
}

select[size],
select[multiple],
select[size][multiple] {
    background: white;
    border: 1px inset gray;
}