修改input 的 placeholder

input::-webkit-input-placeholder, textarea::-webkit-input-placeholder {
color: #666!important;
}
input:-moz-placeholder, textarea:-moz-placeholder {
color: #666!important;
}
input::-moz-placeholder, textarea::-moz-placeholder {
color: #666!important;
}
input:-ms-input-placeholder, textarea:-ms-input-placeholder {
color: #666!important;
}