.banner { overflow: hidden; margin: 2px auto; width: 100%; }

.banner .arr_left { position: absolute; width: 30px; background: url(ent_zxh_0420_arrleft.png) no-repeat; height: 44px; top: 140px; cursor: pointer; left: -1px; _background: none; }
.banner .arr_right { position: absolute; width: 30px; background: url(ent_zxh_0420_arrright.png) no-repeat; height: 44px; top: 140px; cursor: pointer; right: -1px; _background: none; }
.banner A.arr_left:hover { background: url(ent_zxh_0420_arrleft_hover.png) no-repeat; _background: none; }
.banner A.arr_right:hover { background: url(ent_zxh_0420_arrright_hover.png) no-repeat; _background: none; }
.banner .box { float: left; overflow: hidden; width: 100%; max-width:640px; height:auto; }
.banner img {width: 640px; }