//Si el Explorador es...

//Firefox 2
if (navigator.userAgent.toLowerCase().indexOf('firefox/2') > -1)
document.write('<style type="text/css"> \
a, span, img {display:-moz-inline-box;} \
.TB_overlayBG {-moz-opacity:0.75;} \
#TB_HideSelect {-moz-opacity:0;} \
</style>');

//Internet Explorer 6
if (navigator.userAgent.toLowerCase().indexOf('ie 6') > -1)
document.write('<style type="text/css"> \
a {color:expression(this.parentNode.currentStyle.color);} \
.heading_sub form {margin-top:23px} \
/*.home-nav, .contacto-nav, .sitemap-nav {background-image:url(../css/img/header-nav.gif)*/ \
</style>');

//Internet Explorer 7
if (navigator.userAgent.toLowerCase().indexOf('ie 7') > -1)
document.write('<style type="text/css"> \
a {color:expression(this.parentNode.currentStyle.color);} \
</style>');

//Safari
if (navigator.userAgent.toLowerCase().indexOf('safari') > -1)
document.write('<style type="text/css"> \
textarea {resize:none;} \
</style>');

//Google Chrome
if (navigator.userAgent.toLowerCase().indexOf('chrome') > -1)
document.write('<style type="text/css"> \
textarea {resize:none;} \
</style>');

//Opera
if (navigator.userAgent.toLowerCase().indexOf('opera') > -1)
document.write('<style type="text/css"> \
\
</style>');