Mobile Friendly HTML 5 and CSS 3 Responsive Fixed Navigation Menu

index.html

<header>
    <div id="logo" class="menuUp">
        <h1>Adam Bray.</h1>
        <div id="navToggle"><a href="#">Menu</a></div>
    </div>
    <nav>
        <ul>
            <li><a href="#">Home</a></li>
            <li><a href="#">About</a></li>
            <li>
                <a href="#">Blog</a>
                <nav>
                    <ul>
                        <li><a href="#">Articles</a></li>
                        <li><a href="#">Tutorials</a></li>
                        <li><a href="#">Humour</a></li>
                        <li><a href="#">Gaming</a></li>
                        <li><a href="#">Music</a></li>
                    </ul>
                </nav>
            </li>
            <li><a href="#">Forum</a></li>
            <li><a href="#">Help</a></li>
        </ul>
    </nav>
</header>

Mobile Friendly HTML 5 and CSS 3 Responsive Fixed Navigation Menu.markdown

Mobile Friendly HTML 5 and CSS 3 Responsive Fixed Navigation Menu ('-' * 65) A mobile first flexbox navigation menu with a responsive design that works seamlessly with a mobile drop down menu.

A Pen by lawnch on CodePen.

License.

script.js

$(document).ready(function() {
    $("#navToggle a").click(function(e){
        e.preventDefault();
        
        $("header > nav").slideToggle("medium");
        $("#logo").toggleClass("menuUp menuDown");
    });
    
    $(window).resize(function() {
        if($( window ).width() >= "600") {
            $("header > nav").css("display", "block");
            
            if($("#logo").attr('class') == "menuDown") {
                $("#logo").toggleClass("menuUp menuDown");
            }
        }
        else {
            $("header > nav").css("display", "none");
        }
    });
    
    $("header > nav > ul > li > a").click(function(e) {
        if($( window ).width() <= "600") {
            if($(this).siblings().size() > 0 ) {
                $(this).siblings().slideToggle("fast");
            }
        }
    });
});

style.css

* {
    margin: 0;
    padding: 0;
    outline: none;
    
    -webkit-box-sizing: border-box;
    -moz-box-sizing: border-box;
    box-sizing: border-box;
}

body {
    background: #eee;
    color: #444;
    -webkit-font-smoothing: antialiased;
    font-family: "HelveticaNeue-Light", "Helvetica Neue Light", "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; 
    font-weight: 300;
    font-weight: 400;
    height: auto !important;
    height: 100%;
    min-height: 100%;
    text-rendering: optimizeLegibility;
}

header {
    background-color: rgb(140, 193, 193);
    border-bottom: 1px solid rgba(0,0,0,.15);
    display: flex;
    flex-direction: column;
    text-align: center;
}

    header > div#logo {
        line-height: 70px;
        position: relative;
    }
    
    header > .menuDown {
        box-shadow: 0 3px 5px rgba(0,0,0,.15);
    }
    
    header > .menuUp {
        box-shadow: none;
    }
    
        header > div#logo > h1 {
            color: white;
            font-weight: 300;
            text-transform: lowercase;
        }
        
        header > div#logo > div#navToggle {
            background-color: rgba(0,0,0,.15);
            position: absolute;
            right: 0;
            top: 0;
            transition: 300ms all ease;
        }
            
            header > div#logo > div#navToggle:hover {
                background-color: rgba(0,0,0,.1);
            }
            
            header > div#logo > div#navToggle > a {
                color: rgba(255,255,255,.85);
                display: block;
                font-size: 0.85em;
                font-weight: 600;
                padding: 0 2.5rem;
                text-decoration: none;
                transition: 300ms all ease;
            }
            
                header > div#logo > div#navToggle:hover > a {
                    color: rgba(255,255,255,1);
                }

    header > nav {
        background-color: white;
        display: none;
        flex: 1;
        transform: 300ms all ease;
    }
    
        header nav > ul {
            list-style-type: none;    
        }
        
            header nav > ul > li {
                border-bottom: 1px dotted rgba(0,0,0,.1);
                position: relative;
            }
            
                header nav > ul > li:last-of-type {
                    border-bottom: none;    
                }
            
                header nav > ul > li > a {
                    display: block;
                    color: rgba(0,0,0,.65);
                    font-weight: 700;
                    padding: 1.5rem 0;
                    text-decoration: none;
                    transition: 250ms all ease;
                }
                
                    header > nav > ul > li:hover > a {
                        color: rgb(140, 193, 193);    
                    }
                
            header > nav > ul > li > nav {
                background-color: rgb(51,51,51);
                border-radius: 1.5em;
                box-shadow: 0 2px 8px rgba(0,0,0,.6);
                display: none;
                overflow: hidden;
                position: absolute;
                right: 5%;
                width: 90%;
                z-index: 100;
            }
            
                header > nav > ul > li > nav > ul > li > a {
                    color: rgba(255,255,255,.85);
                    transition: 300ms all ease;
                }
                
                    header > nav > ul > li > nav > ul > li:hover > a {
                        background-color: rgba(0,0,0,.6);
                        color: rgba(255,255,255,1);
                    }

/* Medium screens */
@media all and (min-width: 600px) {
    header > div#logo > div#navToggle {
        display: none;    
    }
    
    header {
        background-color: white;
        flex-direction: row;
        line-height: 90px;
        padding: 0 3rem;
		position: fixed;
        text-align: left;
		width: 100%;
    }
    
        header > div#logo {
            background-color: transparent;
            line-height: 90px;
        }
    
            header > div#logo > h1 {
                color: rgb(140, 193, 193);
            }
            
    header > nav {
        background-color: transparent;
        display: block;
    }
    
        header > nav > ul {
            display: flex;
            flex-flow: row wrap;
            justify-content: flex-end;    
        }
        
            header nav > ul > li {
                border-bottom: none;
            }
    
                header nav > ul > li > a {
                    padding: 0 1.25rem;
                }
    
    header > nav > ul > li:hover > nav {
        background-color: rgb(51,51,51);
        border-radius: .25em;
        box-shadow: 0 2px 8px rgba(0,0,0,.6);
        display: block;
        line-height: 3em;
        right: -50%;
        width: 196px;
    }
}