Código CSS

    *{
        padding: 0;
        margin: 0;
        text-decoration: none;
        list-style: none;
        box-sizing: border-box;
    }
    
    nav{
        background: #2fcdcd;
        height: 80px;
        width: 100%;
    }
    .enlace{
        position: absolute;
        padding: 20px 50px;
    }
    .logo{
        height: 40px;
    }
    nav ul{
        float: right;
        margin-right: 20px;
    }
    nav ul li{
        display: inline-block;
        line-height: 80px;
        margin: 0 5px;
    }
    nav ul li a{
        color: #fff;
        font-size: 18px;
        padding: 7px 13px;
        border-radius: 3px;
        text-transform: uppercase;
    }
    li a.active, li a:hover{
        background: #000090;
        transition: .5s;
    }
    .checkbtn{
        font-size: 30px;
        color: #fff;
        float: right;
        line-height: 80px;
        margin-right: 40px;
        cursor: pointer;
        display: none;
    }
    #check{
        display: none;
    }
    section{
        background: url(fondo.jpg) no-repeat;
        background-size: cover;
        background-position: center center;
        height: calc(100vh - 80px);
    }
    
    @media (max-width: 952px){
        .enlace{
            padding-left: 20px;
        }
        nav ul li a{
            font-size: 16px;
        }
    }
    
    @media (max-width: 858px){
        .checkbtn{
            display: block;
        }
        ul{
            position: fixed;
            width: 100%;
            height: 100vh;
            background: #2c3e50;
            top: 80px;
            left: -100%;
            text-align: center;
            transition: all .5s;
        }
        nav ul li{
            display: block;
            margin: 50px 0;
            line-height: 30px;
        }
        nav ul li a{
            font-size: 20px;
        }
        li a:hover, li a.active{
            background: none;
            color: red;
        }
        #check:checked ~ ul{
            left:0;
        }
    }