function menubranco(botao){
      document.getElementById("bthome").src = "imagens/home_preto.png";
   	  document.getElementById("btmoreno").src = "imagens/moreno_preto.png";
	  document.getElementById("btportifolio").src = "imagens/portifolio_preto.png";
	  document.getElementById("btclientes").src = "imagens/clientes_preto.png";
	  document.getElementById("btcontato").src = "imagens/contato_preto.png";
      if(botao == "home"){
         document.getElementById("bthome").src = "imagens/home.png";
	  }else{
         if(botao == "moreno"){
            document.getElementById("btmoreno").src = "imagens/btmoreno.png";
	     }else{
            if(botao == "portifolio"){
            document.getElementById("btportifolio").src = "imagens/portifolio.png";
	        }else{
               if(botao == "clientes"){
                  document.getElementById("btclientes").src = "imagens/clientes.png";
	           }else{
                  if(botao == "contato"){
                     document.getElementById("btcontato").src = "imagens/contato.png";
	              }
			   }
			}
		 }  
	  }
   }