* {
    box-sizing: border-box;
}

.overlay {
    position: fixed;
    top: 0;
    right: 0;
    left: 0;
    bottom: 0;
    z-index: 1;
    background: rgba(0, 0, 0, 0.5);
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s;
}

.overlay.visible {
    opacity: 1;
}

/* Nav */

#nav-main {
    width: 20%;
    height: 100%;
    position: fixed;
    left: 2000px;
    z-index: 2;
    background: #fff;
    transition: all 0.5s;
    text-transform: uppercase;
}

#nav-main a {
    font-size: 14px;
    text-decoration: none;
    color: #000;
}

#nav-main a:hover {
    /*text-decoration: underline;*/
    font-weight: 300;
    /*color: #000;*/
    color: rgba(0, 0, 0, 0.5);
}

.left10 {
    padding-left: 15px;
}

#nav-main.open {
    left: 80%;
    /*    right: 0;*/
}

#nav-main ul {
    padding: 40px 0 0 0;
    list-style: none;
}

#nav-main li {
    margin: 16px 24px;
}


/* Nav button. Nav button animation credit: Nick Salloum
http://callmenick.com/post/animating-css-only-hamburger-menu-icons */

#nav-button {
    display: block;
    position: fixed;
    top: 15px;
    right: 15px;
    z-index: 3;
    overflow: hidden;
    margin: 0;
    padding: 0;
    width: 48px;
    height: 48px;
    font-size: 0;
    text-indent: -9999px;
    background: #000;
    -webkit-appearance: none;
    -moz-appearance: none;
    appearance: none;
    border-radius: 10%;
    border: none;
    box-shadow: 2px 5px 15px 2px rgba(0, 0, 0, 0.3);
    cursor: pointer;
    transition: box-shadow 0.3s, transform 0.3s;
}

#nav-button.hidden {
    transform: translateY(0px);
}

#nav-button:focus {
    outline: none;
}

#nav-button span {
    display: block;
    position: absolute;
    top: 23px;
    left: 16px;
    right: 16px;
    height: 2px;
    background: #fff;
}

#nav-button span::before,
#nav-button span::after {
    position: absolute;
    display: block;
    left: 0;
    width: 100%;
    height: 2px;
    background-color: #fff;
    content: "";
}

#nav-button span::before {
    top: -6px;
}

#nav-button span::after {
    bottom: -6px;
}


/* Nav button animation */

#nav-button span {
    transition: transform 0.3s;
}

#nav-button span::before {
    transform-origin: top right;
    transition: transform 0.3s, width 0.3s, top 0.3s;
}

#nav-button span::after {
    transform-origin: bottom right;
    transition: transform 0.3s, width 0.3s, bottom 0.3s;
}


/* Menu open */

#nav-button.open {
    box-shadow: none;
}

#nav-button.open span {
    transform: rotate(180deg);
}

#nav-button.open span::before,
#nav-button.open span::after {
    width: 50%;
}

#nav-button.open span::before {
    top: 0;
    transform: translateX(10px) translateY(1px) rotate(45deg);
}

#nav-button.open span::after {
    bottom: 0;
    transform: translateX(10px) translateY(-1px) rotate(-45deg);
}