function service()
  {
    document.getElementById("service_mp").style.display = "block";
    document.getElementById("bio_mp").style.display = "none";
    document.getElementById("contact_mp").style.display = "none";
    document.getElementById("feedback_mp").style.display = "none";
  }

function bio()
  {
    document.getElementById("service_mp").style.display = "none";
    document.getElementById("bio_mp").style.display = "block";
    document.getElementById("contact_mp").style.display = "none";
    document.getElementById("feedback_mp").style.display = "none";
  }

function contact()
  {
    document.getElementById("service_mp").style.display = "none";
    document.getElementById("bio_mp").style.display = "none";
    document.getElementById("contact_mp").style.display = "block";
    document.getElementById("feedback_mp").style.display = "none";
  }

function feedback()
  {
    document.getElementById("service_mp").style.display = "none";
    document.getElementById("bio_mp").style.display = "none";
    document.getElementById("contact_mp").style.display = "none";
    document.getElementById("feedback_mp").style.display = "block";
  }