background: -webkit-linear-gradient(left, #29c5db , #63abf0); /* Safari 5.1 - 6.0 *
      
    background: -o-linear-gradient(right,  #29c5db , #63abf0); /* Opera 11.1 - 12.0 */
      
    background: -moz-linear-gradient(right, #29c5db , #63abf0); /* Firefox 3.6 - 15 */
      
    background: linear-gradient(to right,  #29c5db , #63abf0); /* 標準的語法 */