* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

.menu-practicas {
    position: relative;
    display: inline-block;
}
.submenu {
    display: none;
    position: absolute;
    left: 0;
    top: 100%;
    background-color: #1a2c42;
    min-width: 200px;
    padding: 10px 0;
    z-index: 999;
}
.menu-practicas:hover .submenu,
.submenu:hover {
    display: block;
}
.submenu a {
    display: block;
    color: white;
    padding: 8px 15px;
    text-decoration: none;
}
.submenu a:hover {
    background-color: #1565c0;
}


.main-nav {
    margin-top: 10px;
    list-style: none;
    padding-left: 0;
    background-color: #13a4a4;
}
.main-nav-item {
    display: inline-block;
    border-right: 1px solid #ffffff;
}
.main-nav-item a {
    color: #ffffff;
    padding: 2px 8px;
    text-decoration: none;
    border-radius: 2px;
    /*background-color: red;*/
}
.main-nav-item a:hover {
    color: blue;
}
.main-nav-item a:active {
    color: rgb(174, 45, 244);
}
main {
    width: 100%;
    height: 500px;
    border: 10px solid gray;
    padding: 20px 35px;
}