.fs-navbar {
  z-index: 9999;
  position: fixed;
  top: 0;
  width: 100%;
  background: transparent;
}
.fs-navbar.active {
  background: #fff;
  color: #000;
}
.fs-nav-bar {
  position: relative;
}
.fs-nav-back {
  position: absolute;
  top: 0;
  left: 0;
  width: 72rpx;
  height: 100%;
  background: url(https://fs-ad-web-resources.oss-cn-hangzhou.aliyuncs.com/mina/icon_back_white.png) no-repeat;
  background-position: center;
  background-size: 40rpx 40rpx;
}
.fs-navbar.active .fs-nav-back {
  background: url(https://fs-ad-web-resources.oss-cn-hangzhou.aliyuncs.com/mina/icon_back_black.png) no-repeat;
  background-position: center;
  background-size: 40rpx 40rpx;
}
.fs-nav-title {
  display: flex;
  justify-content: center;
  align-items: center;
  width: 100%;
  height: 100%;
  color: #fff;
  font-weight: bold;
  font-size: 34rpx;
}
.fs-navbar.active .fs-nav-title {
  color: #000;
}