纯CSS3编写的红色下拉导航菜单特效代码

一款纯css3 transition属性制作红色的导航菜单，鼠标悬停展开下拉菜单，支持三级下拉菜单代码。
@charset "utf-8";
/*导航栏*/
.nav_menu3,
.nav_menu3 ul,
.nav_menu3 ul li,
.nav_menu3 ul li a,
.nav_menu3 #menu-button {
  margin: 0;
  padding: 0;
  border: 0;
  list-style: none;
  line-height: 1;
  display: block;
  position: relative;
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
}
.nav_menu3 #menu-button { 
    margin-top: 100px;
    background: #F00;
    position: absolute;
    z-index: 99999;
}
.nav_menu3:after,
.nav_menu3 > ul:after {
  content: ".";
  display: block;
  clear: both;
  visibility: hidden;
  line-height: 0;
  height: 0;
}
.nav_menu3 #menu-button {
  display: none;
}
.nav_menu3 {
  width: auto;
  line-height: 1;
  background: #ffffff;
  background: #990B2C;
}
#menu-line {
  position: absolute;
  top: 0;
  left: 0;
  height: 3px;
  background: #990B2C;
  -webkit-transition: all 0.25s ease-out;
  -moz-transition: all 0.25s ease-out;
  -ms-transition: all 0.25s ease-out;
  -o-transition: all 0.25s ease-out;
  transition: all 0.25s ease-out;
}
.nav_menu3 > ul > li {
  float: left;
}
.nav_menu3.align-center > ul {
  font-size: 0;
  text-align: center;
}
.nav_menu3.align-center > ul > li {
  display: inline-block;
  float: none;
}
.nav_menu3.align-center ul ul {
  text-align: left;
}
.nav_menu3.align-right > ul > li {
  float: right;
}
.nav_menu3.align-right ul ul {
  text-align: right;
}
.nav_menu3 > ul > li > a {
  padding: 30px 10px 29px 10px;
  text-decoration: none;
  text-transform: uppercase;
  color: #eee;
  -webkit-transition: color .2s ease;
  -moz-transition: color .2s ease;
  -ms-transition: color .2s ease;
  -o-transition: color .2s ease;
  transition: color .2s ease;
  border-right:1px solid #990B2C;
}
.nav_menu3 > ul > li:hover > a {
  color: #990B2C;
  background: #FFF;
}
.nav_menu3 > ul > li.nav-has-sub > a {
  padding-right: 25px;
}
.nav_menu3 > ul > li.nav-has-sub > a::after {
  position: absolute;
  top: 35px;
  right: 10px;
  width: 4px;
  height: 4px;
  border-bottom: 1px solid #990B2C;
  border-right: 1px solid #990B2C;
  content: "";
  -webkit-transform: rotate(45deg);
  -moz-transform: rotate(45deg);
  -ms-transform: rotate(45deg);
  -o-transform: rotate(45deg);
  transform: rotate(45deg);
  -webkit-transition: border-color 0.2s ease;
  -moz-transition: border-color 0.2s ease;
  -ms-transition: border-color 0.2s ease;
  -o-transition: border-color 0.2s ease;
  transition: border-color 0.2s ease;
}
.nav_menu3 > ul > li.nav-has-sub:hover > a::after {
  border-color: #990B2C;
}
.nav_menu3 ul ul {
  position: absolute;
  left: -9999px;
}
.nav_menu3 > ul > li > ul {    
  border-top: 1px solid #FFF;
}
.nav_menu3 li:hover > ul {
  left: auto;
}
.nav_menu3.align-right li:hover > ul {
  right: 0;
}
.nav_menu3 ul ul ul {
  margin-left: 100%;
  top: 0;
}
.nav_menu3.align-right ul ul ul {
  margin-left: 0;
  margin-right: 100%;
}
.nav_menu3 ul ul li {
  height: 0;
  -webkit-transition: height .2s ease;
  -moz-transition: height .2s ease;
  -ms-transition: height .2s ease;
  -o-transition: height .2s ease;
  transition: height .2s ease;
}
.nav_menu3 ul li:hover > ul > li {
  height: 52px;
}
.nav_menu3 ul ul li a {
  padding: 20px 20px;
  width: 140px;
  background: #990B2C;
  text-decoration: none;
  color: #eeeeee;
  -webkit-transition: color .2s ease;
  -moz-transition: color .2s ease;
  -ms-transition: color .2s ease;
  -o-transition: color .2s ease;
  transition: color .2s ease;
  border-top: 1px solid #990B2C;
}
.nav_menu3 ul ul li:hover > a,
.nav_menu3 ul ul li a:hover {
  color: #990B2C;
  background: #FFF;
  border-top: 1px solid #FFF;
}
.nav_menu3 ul ul li.nav-has-sub > a::after {
  position: absolute;
  top: 25px;
  right: 10px;
  width: 4px;
  height: 4px;
  border-bottom: 1px solid #eee;
  border-right: 1px solid #eee;
  content: "";
  -webkit-transform: rotate(-45deg);
  -moz-transform: rotate(-45deg);
  -ms-transform: rotate(-45deg);
  -o-transform: rotate(-45deg);
  transform: rotate(-45deg);
  -webkit-transition: border-color 0.2s ease;
  -moz-transition: border-color 0.2s ease;
  -ms-transition: border-color 0.2s ease;
  -o-transition: border-color 0.2s ease;
  transition: border-color 0.2s ease;
}
.nav_menu3.align-right ul ul li.nav-has-sub > a::after {
  right: auto;
  left: 10px;
  border-bottom: 0;
  border-right: 0;
  border-top: 1px solid #dddddd;
  border-left: 1px solid #dddddd;
}
.nav_menu3 ul ul li.nav-has-sub:hover > a::after {
  border-color: #990B2C;
}