function report_close() {
  ob = document.getElementById('error_report');
  ob2 = document.getElementById('courtain');
  ob.style.display = "none";
  ob2.style.display = "none";
}

function report_open() {
  ob = document.getElementById('error_report');
  ob2 = document.getElementById('courtain');
  ob.style.display = "block";
  ob2.style.display = "block";
  
  width = document.body.offsetWidth;
  height = document.body.offsetHeight;
  
  wh = alertSize();
  
  widthCont = ob.offsetWidth;
  heightCont = ob.offsetHeight;
  
  ob.style.left = (wh[0]/2-widthCont/2)+'px';
  ob.style.top = (wh[1]/2-heightCont/2)+'px';
}

function alertSize() {
  var myWidth = 0, myHeight = 0;
  if( typeof( window.innerWidth ) == 'number' ) {
    //Non-IE
    myWidth = window.innerWidth;
    myHeight = window.innerHeight;
  } else if( document.documentElement && ( document.documentElement.clientWidth || document.documentElement.clientHeight ) ) {
    //IE 6+ in 'standards compliant mode'
    myWidth = document.documentElement.clientWidth;
    myHeight = document.documentElement.clientHeight;
  } else if( document.body && ( document.body.clientWidth || document.body.clientHeight ) ) {
    //IE 4 compatible
    myWidth = document.body.clientWidth;
    myHeight = document.body.clientHeight;
  }
  return [ myWidth, myHeight ];
}