Resonsive Navigation für Mobile, Tablet & Desktop

    Halloo, ich brauche eine responsive Navigation für Mobile, Tablet & Desktop Anwendungen.
    Momentan habe ich die Navigation an meine Bildschirmgröße mit 180px angepasst,
    allerdings weiß ich nicht wie ich nun weiter komme :confused:

    Mein css file dazu:
    nav ul ul {
    display: none;
    }

    nav ul li:hover > ul {
    display: block;
    }

    nav ul {
    background: #efefef;
    background: linear-gradient(top, #efefef 0%, #56b29e 90%);
    background: -moz-linear-gradient(top, #efefef 0%, #56b29e 90%);
    background: -webkit-linear-gradient(top, #efefef 0%, #56b29e 90%);
    box-shadow: 0px 0px 9px rgba(86, 178, 158, 0.15);
    padding: 0 20px;
    border-radius: 10px;
    list-style: none;
    position: relative;
    display: inline-table;
    }
    nav ul:after {
    content: ""; clear: both; display: block;
    }

    nav ul li {
    float: left;
    }
    nav ul li:hover {
    background: #4b545f;
    background: linear-gradient(top, #4f5964 0%, #5f6975 40%);
    background: -moz-linear-gradient(top, #4f5964 0%, #5f6975 40%);
    background: -webkit-linear-gradient(top, #4f5964 0%,#5f6975 40%);
    }
    nav ul li:hover a {
    color: #fff;
    }

    nav ul li a {
    display: block; padding: 16px 180px;
    color: rgba(0, 0, 0, 0.98); text-decoration: none; font-size:13pt;
    }

    nav ul ul {
    background: #5f6975; border-radius: 0px; padding: 0;
    position: absolute; top: 100%;
    }
    nav ul ul li {
    float: none;
    border-top: 1px solid #6b727c;
    border-bottom: 1px solid #575f6a;
    position: relative;
    }
    nav ul ul li a {
    padding: 15px 40px;
    color: #fff;
    }
    nav ul ul li a:hover {
    background: #4b545f;
    }

    Mein html file:

    <nav>
    <ul>
    <li><a href="DesignVorlage.html">Übersicht</a>
    <ul>
    <li><a href="#">Übersicht 1</a></li>
    <li><a href="#">Übersicht 2</a></li>
    </ul>
    </li>
    <li><a href="Taetigkeitenerfassung.php">Tätigkeit</a></li>
    <li><a href="index.php"><span class="glyphicon glyphicon-log-out"></span> Abmelden</a></li>
    </ul>
    </nav>

    Momentane Sicht: