html, body, div, ul, ol, li, p, h1, h2, h3, h4, h5, h6, dl, dt, dd, input, form, select, a, img, em, span, strong, table, tbody, th, tr, td, textarea, iframe, button { margin: 0px; padding: 0px; }
img, button, embed { vertical-align: top; border: 0px none; }
input, textarea { border: 0px none; outline: none; }
ul, ol, li { list-style: none; }
a, a:visited { font-size: 100%; text-decoration: none; }
a:hover { color: rgb(1, 116, 196); }
i, em { font-style: normal; }
b { font-weight: normal; }
html, body { width: 100%; }
iframe { margin-bottom: -5px; }
body, textarea { font: 14px/1.5em 微软雅黑, "Microsoft YaHei", simsun, sans-serif, Arial; }
body { color: rgb(0, 0, 0); min-width: 1200px; }
.download {  width: 1027px;
    height: 76px;
    position: absolute;
    top: 840px;
    left: 50%;
    margin-left: -618px;
    z-index: 1500;}
.btn_1 { width: 261px; height: 132px; text-align: center; font-size: 13px; color: rgb(0, 0, 0); margin-left: 140px; background: url("../images/btn1.png") left top no-repeat; display: block; transition: letter-spacing 0.3s ease-in 0s; }
.btn_1:hover { background: url("../images/btn1-h.png") left top no-repeat; letter-spacing: 4px; }
.btn_2 { width: 261px; height: 132px; text-align: center; font-size: 13px; color: rgb(0, 0, 0); margin-top: -132px; margin-left: 490px; background: url("../images/btn2.png") right top no-repeat; display: block; transition: letter-spacing 0.3s ease-in 0s; }
.btn_2:hover { background: url("../images/btn2-h.png") left top no-repeat; letter-spacing: 4px; }
.btn_3 { width: 261px; height: 132px; text-align: center; font-size: 13px; color: rgb(0, 0, 0); margin-top: -132px; margin-left: 840px; background: url("../images/btn3.png") right top no-repeat; display: block; transition: letter-spacing 0.3s ease-in 0s; }
.btn_3:hover { background: url("../images/btn3-h.png") left top no-repeat; letter-spacing: 4px; }