.header {
  height: 100px;
  background: #004d99;
  box-shadow: 0px 0px 6px rgba(0, 0, 0, 0.2);
}

.header-logo {
  color: #fff;
  display: inline-block;
  line-height: 51px;
  margin-top: 25px;
  font-weight: bold;
  font-size: 28px;
}

.header-menu {
  float: right;
}

.header-menu > li {
  float: left;
  margin: 0 35px;
  position: relative;
  line-height: 100px;
}

.header-menu > li > a {
  color: #fff;
}
.header-menu li a {
  cursor: pointer;
  font-weight: bold;
}

.header-menu > li:hover .header-menu_child {
  height: auto;
}

.header-menu_child {
  position: absolute;
  left: 50%;
  margin-left: -70px;
  top: 90px;
  box-shadow: 0 0 5px rgba(0, 0, 0, 0.5);
  height: 0;
  z-index: 100;
  border-radius: 5px;
  overflow: hidden;
  transition: all 0.2s;
  font-size: 14px;
}

.header-menu_child > li a {
  height: 30px;
  display: block;
  padding: 8px 12px;
  min-width: 140px;
  line-height: 30px;
  background: #fff;
  transition: background 0.2s, color 0.2s;
}
.header-menu_child > li a:hover {
  color: #fff;
  background: #004d99;
}