#slider
{
 width: 100%;
 height: 300px;
 background: white;
 margin: 50px auto;
 background-image: url("../images/slider.jpg"); 
}

.s_element
{
 width: 25%;
 height: 100%;
 float: left;
}

#s_img_1
{
 width: 80%;
 height: 80%;
 background-image: url("../images/top1.jpg");
 background-size: cover;
 margin-left: auto;
 margin-right: auto;
}

#s_img_2
{
 width: 80%;
 height: 80%;
 background-image: url("../images/top2.jpg");
 background-size: cover;
 margin-left: auto;
 margin-right: auto;
}

#s_img_3
{
 width: 80%;
 height: 80%;
 background-image: url("../images/top3.jpg");
 background-size: cover;
 margin-left: auto;
 margin-right: auto;
}


#s_img_4
{
 width: 80%;
 height: 80%;
 background-image: url("../images/top4.jpg");
 background-size: cover;
 margin-left: auto;
 margin-right: auto
}

#introduce
{
 width: 100%;
 height: 300px;
}

#intro_left
{
 width: 70%;
 height: 100%;
 float: left;
 background-image: url("../images/intro_left.jpg");
}

#intro_right
{
 width: 30%;
 height: 100%;
 float: left;
 background-image: url("../images/racket.jpg");
 background-size: cover;
}