.tbsearchbar {
    padding-top: 10px;
    color: red; //To add some color.
}

仅更改占位符颜色：

::-webkit-input-placeholder { /* WebKit browsers */
    color:    #909;
}
:-moz-placeholder { /* Mozilla Firefox 4 to 18 */
   color:    #909;
   opacity:  1;
}
::-moz-placeholder { /* Mozilla Firefox 19+ */
   color:    #909;
   opacity:  1;
}
:-ms-input-placeholder { /* Internet Explorer 10+ */
   color:    #909;
}