.nav {
background: white;
text-align: center;
}
.nav a {
text-decoration: none;
display: block;
transition: .5s linear;
}
.nav ul {
list-style: none;
margin: 0;
padding: 0;
}
.topmenu > li {
display: block;
/*Если вместо block задать inline-block,
меню будет горизонтальным*/
position: relative;
width: 500px;
}
.topmenu > li > a {
font-weight: bold;
padding: 10px 30px;
font-size: 12px;
text-transform: uppercase;
letter-spacing: 2px;
color: #1c1c1c;
border: 1px solid #999;
}
.submenu {
position: absolute;
left: 500px;
z-index: 5;
width: 500px;
visibility: hidden;
opacity: 0;
transform: translateY(10px);
transition: .5s ease-in-out;
}
.submenu li {
position: relative;
border: 1px solid #999;
margin:2px;
}
.submenu a {
background: white;
color: #1c1c1c;
text-align: center;
font-size: 14px;
letter-spacing: 1px;
padding: 10px 20px;
}
.submenu .submenu {
position: absolute;
top: 0;
left: 500px;

}
.nav li:hover > .submenu {
visibility: visible;
opacity: 1;
transform: translateY(0px);
}