* {
  margin: 0;
  padding: 0;
  font-size: 0;
}

body {
  width: 100vw;
  height: 100vh;
}

.nav_bar {
  width: 100%;
  background-size: 100% 100%;
  z-index: 999;
  position: relative;
}

.nav_bar_bg {
  width: 100%;
  height: 0.88rem;
  background-image: url("../img/nav_bar.png");
  background-size: 100% center;
  position: relative;
}

.menu_btn {
  width: 0.44rem;
  height: 0.35rem;
  position: absolute;
  left: 0.3rem;
  top: 50%;
  transform: translateY(-50%);
}

.drop_down {
  background-color: #222149;
  padding: 0.5rem 0.84rem;
  box-sizing: border-box;
  position: absolute;
  bottom: 0;
  transform: translateY(100%);
  left: 0;
  width: 100%;
  display: none;
}

.drop_down a {
  display: block;
  color: #74748d;
  font-size: 0.32rem;
  height: 0.8rem;
  line-height: 0.8rem;
  text-decoration: none;
}

.nav_bar_icon {
  width: 1.71rem;
  height: 0.6rem;
}

.horizontal_vertical_center {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}