function backToTop() {
  var x1 = x2 = x3 = 0;
  var y1 = y2 = y3 = 0;
  if (document.documentElement) {
      x1 = document.documentElement.scrollLeft || 0;
      y1 = document.documentElement.scrollTop || 0;
  }
  if (document.body) {
      x2 = document.body.scrollLeft || 0;
      y2 = document.body.scrollTop || 0;
  }
  x3 = window.scrollX || 0;
  y3 = window.scrollY || 0;
  var x = Math.max(x1, Math.max(x2, x3));
  var y = Math.max(y1, Math.max(y2, y3));
  window.scrollTo(Math.floor(x / 2), Math.floor(y / 2));
  if (x > 0 || y > 0) {
      window.setTimeout("backToTop()", 25);
  }
}


/**
 * jQueryRollover v1.0.1
 * http://rewish.org/javascript/jquery_rollover_plugin
 *
 * Copyright (c) 2009 Rewish (http://rewish.org/)
 *
 * Licensed under the MIT:
 * [en] http://www.opensource.org/licenses/mit-license.php
 * [ja] http://sourceforge.jp/projects/opensource/wiki/licenses%2FMIT_license
 *
 * Inspired by:
 * Telepath Labs (http://dev.telepath.co.jp/labs/article.php?id=15)
 *
 * Usage:
 * jQuery(document).ready(function($) {
 *   // <img>
 *   $('div#nav a img').rollover();
 *
 *   // <input type="image">
 *   $('form input:image').rollover();
 *
 *   // set postfix
 *   $('div#nav a img').rollover('_over');
 * });
 *
 **/
(function($) {
    $.fn.rollover = function(postfix) {
        postfix = postfix || '_on';
        return this.not('[src*="'+ postfix +'."]').each(function() {
            var img = $(this);
            var src = img.attr('src');
            var src_on = [
                src.substr(0, src.lastIndexOf('.')),
                src.substring(src.lastIndexOf('.'))
            ].join(postfix);
            $('<img>').attr('src', src_on);
            img.hover(
                function() {
                    img.attr('src', src_on);
                },
                function() {
                    img.attr('src', src);
                }
            );
        });
    };
})(jQuery);

jQuery(document).ready(function($) {
  $('#pagetop a img, #bird img').rollover();
});



// quake
qitv = 5;
qcnt = 0;
x = new Array( 3,-2, 2,-3,0);
y = new Array(-4, 1,-2, 1,4);
function quake() {
  if(x[qcnt] != 0) moveBy(x[qcnt],y[qcnt]);
  qcnt++;
  if(qcnt < x.length) setTimeout("quake()",qitv);
  else qcnt = 0;
}