:root {
    --menuWidth: 16em;
    --menuColor: #353441;
    --menuText: #9DC6D1;
    --menuItemHeight: 60px;
    --degActive: 15deg;
    --degHover: 1deg;
    --timing: 150ms;
    --contentBG: #9DC6D1;
    --bodyBg: #21212D;
}

html,
body {
    height: 100%;
    margin: 0;
    padding: 0;
}

* {
    box-sizing: border-box;
}

body {
    font-family: 'Raleway', sans-serif;
    line-height: 1.7;
    perspective-origin: 0% 50%;
    perspective: 800px;
    background: var(--bodyBg);
}

nav,
main {
    transition: transform var(--timing) ease-out;
}

nav {
    z-index: 100;
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    width: var(--menuWidth);
    background-color: var(--menuColor);
    transform: translateX(-var(--menuWidth));
}

nav.menu-active {
    transform: translateX(0);
}

nav.menu-hover {
    transform: translateX(-calc(var(--menuWidth) - (var(--menuWidth) / 16)));
}

nav h1 {
    z-index: 100;
    display: block;
    right: calc(-var(--menuItemHeight));
    height: var(--menuItemHeight);
    line-height: var(--menuItemHeight);
    font-size: .8em;
    font-weight: 800;
    letter-spacing: 1px;
    color: var(--menuText);
    text-transform: uppercase;
    text-align: center;
    background-color: var(--menuColor);
    cursor: pointer;
}

nav h1:hover {
    color: var(--menuColor);
    background: #ffffff;
}

nav ul {
    margin: 0;
    padding: 0;
}

nav li {
    display: inline-block;
    padding: 0 1em;
    width: 100%;
    height: var(--menuItemHeight);
    color: var(--menuText);
    line-height: var(--menuItemHeight);
    background-color: var(--menuColor);
}

nav li:nth-of-type(2n) {
    background-color: lighten(var(--menuColor), 2%);
}

nav li:hover {
    background: #ffffff;
}

main {
    z-index: 0;
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    display: flex;
    align-items: center;
    overflow: hidden;
    background-color: var(--contentBG);
    transform-origin: 0% 50%;
}

main:after {
    content: '';
    display: block;
    position: absolute;
    z-index: 1;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    background: linear-gradient(to right, transparent, rgba(var(--bodyBg), .5));
    visibility: hidden;
    opacity: 0;
    transition: opacity var(--timing) ease-out, visibility 0s var(--timing);
}

main.menu-active {
    border-radius: .001px;
    transform: translateX(var(--menuWidth)) rotateY(var(--degActive));
}

main.menu-active:after {
    visibility: visible;
    opacity: 1;
    transition: opacity var(--timing) ease-out, visibility 0s;
}

main.menu-hover {
    border-radius: .001px;
    transform: translateX(calc(var(--menuWidth) / 16)) rotateY(var(--degHover));
}

main section {
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    margin: auto;
    padding: 1em 4em;
    max-width: 680px;
    overflow: auto;
    background-color: rgba(255, 255, 255, 0.5);
}

section h1 {
    font-weight: 800;
    text-transform: uppercase;
    font-size: 2em;
}

section p {
    display: inline-block;
    margin: 16px 0;
}

/* Media Queries for Responsiveness */
@media (max-width: 768px) {
    :root {
        --menuWidth: 12em;
        --menuItemHeight: 50px;
    }

    nav h1 {
        font-size: 0.7em;
    }

    main section {
        padding: 1em 2em;
    }
}

@media (max-width: 480px) {
    :root {
        --menuWidth: 10em;
        --menuItemHeight: 40px;
    }

    nav h1 {
        font-size: 0.6em;
    }

    main section {
        padding: 1em;
    }
}