美化思路：首先用CSS代码将Select下拉框默认样式全部去掉，自己为下拉框定义样式；最重要的是下拉框的按钮，也需要用CSS代码隐藏，然后用图片来定义，这样就美观多了。

效果截图：

HTML代码：

<select class="form-control info-select">
    <option selected="selected">1</option>
    <option>2</option>
    <option>3</option>
    <option>4</option>
</select>

CSS代码：

.form-control {
    display: block;
    width: 100%;
    height: 34px;
    padding: 6px 12px;
    font-size: 14px;
    line-height: 1.42857143;
    color: #555;
    background-color: #fff;
    background-image: none;
    border: 1px solid #ccc;
    border-radius: 4px;
    -webkit-box-shadow: inset 0 1px 1px rgba(0,0,0,.075);
    box-shadow: inset 0 1px 1px rgba(0,0,0,.075);
    -webkit-transition: border-color ease-in-out .15s,-webkit-box-shadow ease-in-out .15s;
    -o-transition: border-color ease-in-out .15s,box-shadow ease-in-out .15s;
    transition: border-color ease-in-out .15s,box-shadow ease-in-out .15s;
}

/* IE浏览器下隐藏下拉按钮 */
select::-ms-expand { display: none; }     

/* 定义隐藏下拉框默认样式及图片覆盖下拉按钮 */   
.info-select{
    width: 200px;
    outline:none;
    appearance:none;
    -moz-appearance:none;
    -webkit-appearance:none;
    -ms-appearance:none;
    background: url(img/down.png) no-repeat scroll right center transparent;           
}