Change the color of the Search placeholder text

Hello, Thank you for this plugin! I am using Altitude Pro theme and was wondering how to change the search form’s placeholder text color to white (instead of black.) This is the CSS that I am using, and I swear it worked for a minute, but now it’s back to black:

.genesis-nav-menu li.searchbox form.search-form input[type=”search”]::-moz-placeholder,
.genesis-nav-menu li.searchbox form.searchform input[type=”text”]::-moz-placeholder,
#nav .s::-moz-placeholder,
.genesis-nav-menu li.searchbox form.search-form input[type=”search”]:-moz-placeholder,
.genesis-nav-menu li.searchbox form.searchform input[type=”text”]:-moz-placeholder,
#nav .s:-moz-placeholder,
.genesis-nav-menu li.searchbox form.search-form input[type=”search”]::-webkit-input-placeholder,
.genesis-nav-menu li.searchbox form.searchform input[type=”text”]::-webkit-input-placeholder,
#nav .s::-webkit-input-placeholder,
.genesis-nav-menu li.searchbox form.search-form input[type=”search”]:-ms-input-placeholder,
.genesis-nav-menu li.searchbox form.searchform input[type=”text”]:-ms-input-placeholder,
#nav .s:-ms-input-placeholder {
color: #ffffff !important;
}

Any help is appreciated.