html,
body {
  margin: 0;
  padding: 0;
  font-size: 100px;
  line-height: 1;
  font-family: "Source Han Sans CN" !important;
  color: #333;
  box-sizing: border-box;
  background-color: #F5F7F9;
  user-select: none;
}
.header_root {
  position: fixed;
  width: 100%;
  color: #fff;
  background-color: transparent;
  z-index: 9999;
}
.header_root.bg_white {
  color: #333;
  background-color: #fff;
}
.header_root:hover {
  color: #333;
  background-color: #fff;
} 
.header_root:hover .header_box .header_left .left_white {
  display: none;
}
.header_root:hover .header_box .header_left .left_gray {
  display: inline-block;
}
.footer_root {
  background-color: #F5F7F9;
}