var Mac   = navigator.userAgent.indexOf("Mac") != -1 ? true : false
var cssurl;

if (document.getElementById) {
  if(Mac) cssurl = "../css/fonts_mac.css" // Mac W3C対応ブラウザ用CSS
} else if (document.all) {
  if(Mac) cssurl = "../cssfonts_mac.css"  // Mac IE用CSS
} else if (document.layers) {
  if(Mac) cssurl = "../cssfonts_mac.css"  // Mac N4用CSS
}

document.write('<link rel="stylesheet" ')
document.write('      type="text/css"  ')
document.write('      href="'+cssurl+'"')
document.write('>')