Ghost/ghost/admin/assets/sass/layouts/default.scss

//
// Global Container
// --------------------------------------------------

#container {
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    overflow: hidden;
}

//
// Main Layout
// --------------------------------------------------

// The <main> content wrapper
.viewport {
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    overflow: hidden;
    z-index: 500; // Above the .global-nav when collapsed
    transition: transform $side-outlet-transition-duration cubic-bezier(0.1, 0.7, 0.1, 1);

    @media (max-width: 900px) {
        transition: transform 0.4s cubic-bezier(0.1, 0.7, 0.1, 1);
    }

    // This selector ends up being `body.settings-menu-expanded .viewport`
    body.global-nav-expanded & {
        transform: translate3d(260px, 0px, 0px);
    }

    // This selector ends up being `body.settings-menu-expanded .viewport`
    body.settings-menu-expanded & {
        @media (max-width: 350px) {
            transform: translate3d(-100%, 0px, 0px);
        }
        @media (min-width: 351px) {
            &:before {
                content: '';
                position: absolute;
                top: 0;
                right: 0;
                bottom: 0;
                z-index: 1000;
                width: 1px;
                background: #EDECE4;
            }
            transform: translate3d(-350px, 0px, 0px);
        }
    }
}


//
// The header bar - visible below 900px
// --------------------------------------------------

.page-header {
    position: relative;
    height: 44px;
    line-height: 44px;
    text-align: center;
    color: #fff;
    background: $darkgrey;
    overflow: hidden;

    @media (min-width: 900px) {
        height: 60px;
        line-height: 60px;
    }

}

// Centered page heading
.page-title {
    display: block;
    height: 44px;
    line-height: 44px;
    margin: 0;
    padding: 0 15%;
    color: #fff;
    font-size: 1.8rem;
    font-weight: normal;
    letter-spacing: 0;
    text-overflow: ellipsis;
    white-space: nowrap;
    overflow: hidden;

    @media (min-width: 900px) {
        height: 60px;
        line-height: 60px;
    }
}

// The burger to expand .global-nav menu
.menu-button {
    @include icon($i-menu, 18px) {
        position: absolute;
        top: 50%;
        left: 12px;
        transform: translateY(-50%);
    }
    display: block;
    position: absolute;
    top: 0;
    left: 0;
    width: 44px;
    height: 44px;
    color: #fff;
}


//
// The panel which wraps the main content area
// --------------------------------------------------
// We can't use position:fixed on .page-header because it would
// break the mobile menu. So we create an overflow-auto content
// area which scrolls just underneath the header, making it look
// like the header is position:fixed.

.page-content {
    position: absolute;
    top: 60px;
    right: 0;
    bottom: 0;
    left: 0;
    background: #fff;
    overflow-y: auto;
    overflow-x: hidden;

    @media (max-width: 900px) {
        top: 44px;
    }
}