header nav {
  background-color: #e5f6ff;
}
header nav > ol {
  display: flex;
  width: 1024px;
  margin: auto;
}
header nav > ol > li {
  position: relative;
  width: 20%;
}
header nav > ol > li:nth-child(n + 2) {
  border-left: 1px solid #fff;
}
header nav > ol > li > a {
  display: flex;
  justify-content: center;
  align-items: center;
  width: 100%;
  height: 50px;
  background-color: #afcffa;
  transition: background-color 0.3s ease;
}
header nav > ol > li > a:hover {
  background-color: rgba(175, 207, 250, 0.7);
}
header nav > ol > li > ol {
  position: absolute;
  left: 0;
  top: 100%;
  display: none;
  width: 100%;
}
header nav > ol > li > ol li a {
  display: block;
  padding: 10px;
  border-top: 1px solid #fff;
  background-color: #627899;
  color: #fff !important;
  transition: opacity 0.3s ease;
}
header nav > ol > li > ol li a:hover {
  opacity: 0.8;
}
header nav > ol > li:hover > ol {
  display: block;
}