/* The Overlay (background) */
.overlay {
    /* Height & width depends on how you want to reveal the overlay (see JS below) */
    height: 100%;
    width: 0;
    position: fixed; /* Stay in place */
    z-index: 1; /* Sit on top */
    left: 0;
    top: 0;
    border-right: 1px solid;
    border-right-color: #818181;
    background-repeat: repeat-x repeat-y;
    background-image: url('https://www.mobygo.nl/images/concrete_wall_square.jpg');
    background-size: auto;
    overflow-x: hidden; /* Disable horizontal scroll */
    transition: 0.5s; /* 0.5 second transition effect to slide in or slide down the overlay (height or width, depending on reveal) */
}

/* Position the content inside the overlay */
.overlay-content {
    position: relative;
    top: 25%; /* 25% from the top */
    width: 100%; /* 100% width */
    text-align: center; /* Centered text/links */
    margin-top: 30px; /* 30px top margin to avoid conflict with the close button on smaller screens */
}

/* The navigation links inside the overlay */
.overlay a {
    padding: 8px;
    text-decoration: none;
    font-size: 14px;
    font-family: Arial;
    color: #fff;
    display: block; /* Display block instead of inline */
    transition: 0.3s; /* Transition effects on hover (color) */
}

    /* When you mouse over the navigation links, change their color */
    .overlay a:hover, .overlay a:focus {
        color: darkorange;
    }

/* Position the close button (top right corner) */
.overlay .closebtn {
    position: absolute;
    top: 15px;
    right: 35px;
    font-size: 40px;
}