function formatTime() {
  now = new Date();
  hour = now.getHours();
  min = now.getMinutes();
  sec = now.getSeconds();

  if (min <= 9) {
	min = "0" + min; }
  if (sec <= 9) {
	sec = "0" + sec; }
  if (hour < 10) {
	hour = "0" + hour; }
  document.getElementById('hora').innerHTML = hour + ':' + min;

  setTimeout("formatTime()", 1000);
  if(hour>=18 || hour<=5){
	  if(min>=00){
		document.getElementById('boas-vindas').innerHTML = 'boa noite';
		var htmlBody=document.getElementsByTagName("BODY");
		$('body').removeClass('dia');
		$('body').addClass('noite');
	  }
  } else if((hour>=4 || hour<=18)) {
    if((hour>=4 && hour<=13)){
      if(min>=00){
        document.getElementById('boas-vindas').innerHTML = 'bom dia';
        var htmlBody=document.getElementsByTagName("BODY");
        $('body').removeClass('noite');
        $('body').addClass('dia');
        }
    } else if((hour>=13 && hour<=18)){
      if(min>=00){
        document.getElementById('boas-vindas').innerHTML = 'boa tarde';
        var htmlBody=document.getElementsByTagName("BODY");
        $('body').removeClass('noite');
        $('body').addClass('dia');
        }
    }
  } 
}
window.onload=formatTime;