function change_color(text) {
	var search = document.getElementById('searchtext');
	search.className = '';
	if (search.value == text) {
		search.value = '';
	} else if (search.value == ''){
		search.value = text;
	}
	if (search.value != text) {
		search.className == '' ? search.className = 'black_color' : search.className = '';
	}
}