input file 把之前的按钮透明度opacity设置为0，外层用div包裹。
1 <div class="uploadButDiv greenButton text-center">2 <input type="file" accept="image/jpeg,image/jpg,image/png,image/gif"/>上传4 </div>
.uploadButDiv { ???width: 100%; ???height: 3.25rem; ???line-height: 3.2rem; ???position: relative; ???cursor: pointer; ???color: #0057FF; ???font-size: 1.125rem; ???background: #fff; ???border: 1px solid #0057FF; ???border-radius: 4px; ???overflow: hidden; ???display: inline-block;}.uploadButDiv input { ???width: 100%; ???position: absolute; ???right: 0; ???top: 0; ???opacity: 0; ???cursor: pointer}上传文件input（type=file）美化。
原文地址：http://www.cnblogs.com/Evo1uti0n/p/7606532.html