var mv = new Array;
mv[0]="";
mv[1]="img/top_btn_concept1.jpg";
mv[2]="img/top_btn_concept2.jpg";
mv[3]="img/top_btn_concept3.jpg";
var ran = Math.floor(Math.random()*3)+1;
document.write('<a href="/about/"><img src="' + mv[ran] + '" width="404" height="404" border="0" alt="OZONEだからできる「生活者と企業をつなぐ力」" /></a>');