#banner { 
    overflow:hidden; 
    width:100%; 
    position:relative; 
    float:left;
    padding-bottom: 10px;
}
#tab>img:not(:first-child){ 
    display:none; 
}
.lunbo_btn {
    height: 15px;
    width: 100%;
    margin: 0px auto;
    margin-top: -40px;
    position: absolute;
    z-index: 3;
    text-align: center;
}
.lunbo_btn span {
    width:14px;
    height:14px;
    display:inline-block;
    background-color:#b4b5b7;
    border-radius:50%;
    margin:0px 2px;
    cursor:pointer;
}
.lunbo_btn span.hover {
    background-color:#ffb23c;
}
.arrow {
    display: none;
    width: 30px;
    height: 60px;
    background-color: rgba(0,0,0,0.4);
    position: absolute;
    top: 50%;
    margin-top: -30px;
    z-index:999;
}
.arrow span {
    display: block;
    width: 10px;
    height: 10px;
    border-bottom: 2px solid #fff;
    border-left: 2px solid #fff;
}
.slider_left {
    margin: 25px 0 0 10px;
    transform: rotate(45deg);
}
.prve {
    left: 0;
}
.next {
    right: 0;
}
.slider_right {
    margin: 25px 0 0 5px;
    transform: rotate(-135deg);
}
.arrow:hover{background:#444;}
#banner:hover .arrow{display:block;}