body {
    margin: 0;
    padding: 0;
    border: 0;
}

a {
    color: #fff;
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
}

a:visited {
    color: #fff;
}

.clear {
    clear: both;
}

#header {
    height: 700px;
    background: linear-gradient(135deg, #2b7fc7, #132551);
}

#nav {
    width: 1400px;
    height: 70px;
    margin: 0 auto;
}

.nav-item {
    float: left;
}

.nav-item a {
    display: block;
    width: 150px;
    height: 70px;
    line-height: 70px;
    text-align: center;
    color: #fff;
    font-size: 16px;
    font-weight: 600;
}

#download {
    width: 1400px;
    margin: 0 auto;
}

#download_title_large {
    margin: 100px auto 0 auto;
    width: 460px;
    text-align: center;
    color: #fff;
    font-size: 52px;
    font-style: normal;
    font-weight: 800;
    line-height: 57px;
}

#download_title_small {
    margin: 25px auto 0 auto;
    width: 600px;
    font-style: normal;
    font-weight: 400;
    font-size: 20px;
    line-height: 150%;
    text-align: center;
    color: #fff;
}

#download_button {
    display: block;
    margin: 40px auto 0 auto;
    width: 200px;
    height: 50px;
    line-height: 50px;
    background-color: #14c744;
    border-radius: 5px;
    color: #fff;
    font-size: 20px;
    text-align: center;
}

#buy {
    width: 1400px;
    margin: 0 auto;
}

#buynow {
    margin: 60px auto 0 auto;
    width: 200px;
    font-style: normal;
    font-weight: 400;
    font-size: 14px;
    line-height: 150%;
    text-align: center;
    color: #fff;
}

#payment {
    margin: 15px auto 0 auto;
    width: 460px;
    text-align: center;
    color: #fff;
}

#introduction {
    width: 1400px;
    margin: 0 auto;
}

.introduction_left {
    float: left;
    width: 700px;
    height: 700px;
}

.introduction_right {
    float: left;
    width: 700px;
    height: 700px;
}

#introduction h2 {
    margin: 160px 48px 32px 48px;
    font-size: 38px;
    font-weight: 700;
}

#introduction p {
    margin: 16px 48px 32px 48px;
    font-size: 20px;
    font-weight: 300;
}

#s1 {
    background-image: url(../img/s1.jpg);
    background-repeat: no-repeat;
    background-position: center;
}

#s2 {
    background-image: url(../img/s2.jpg);
    background-repeat: no-repeat;
    background-position: center;
}

#s3 {
    background-image: url(../img/s3.jpg);
    background-repeat: no-repeat;
    background-position: center;
}

#s4 {
    background-image: url(../img/s4.jpg);
    background-repeat: no-repeat;
    background-position: center;
}

#footer {
    height: 160px;
    background-color: #132551;
}

#footer_item {
    width: 1400px;
    height: 160px;
    margin: 0 auto;
    line-height: 160px;
    color: #fff;
    font-size: 20px;
    font-weight: 300;
}