* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
.top {
  margin: 20px 0;
}

.wrap {
  max-width: 1200px;
  margin: 0 auto;
}

.top ul {
  list-style: none;
}
.top ul a {
  color: inherit;
  text-decoration: none;
}

.nav {
  display: flex;
}
.nav li {
  position: relative;
}
.nav > li {
  flex: 1;
}
.nav a {
  display: block;
  text-align: center;
  line-height: 2.5;
}
.nav > li > a {
  font-size: 16px;
  color: #000;
}
.sub-nav {
  position: absolute;
  width: 100%;
  display: none;
  background: #efefef;
}
.sub-nav li {
  border-bottom: 1px solid rgba(0, 0, 0, 0.1);
}
.sub-nav > li > a {
  font-size: 14px;
  color: #333;
}

.third-nav {
  position: absolute;
  display: none;
  top: 0;
  left: 100%;
  width: 100%;
  background: #ccc;
}
.third-nav > li > a {
  font-size: 12px;
  color: #666;
}
.nav > li:hover .sub-nav {
  display: block;
}

.sub-nav > li:hover .third-nav {
  display: block;
}