#content_container {
    position: relative;
}

/* navigation */
#nav_container {
    z-index: 5;
    position: absolute;
    top: 0;
    text-align: center;
    margin: 0 auto;
    width: 100%;
    max-height: 100px;
    height: 8.5vw;
}

.nav_buttons {
    width: 100%;
    max-width: 1080px;
    height: 100%;
    display: inline-block;
    position: relative;
    margin: 0 auto;
    padding: 0;
    list-style: none;
}

.nav_button_container {
    display: inline-block;
    position: relative;
    height: 100%;
    width: 25%;
    margin: 0 10px 0 0;
}

.nav_button_background {
    position: relative;
    top: 0;
    left: 0;
    height: 100%;
    background: url(../assets/images/nav/nav_button_blue.png) no-repeat;
    background-size: 100% 100%;
}
.nav_button_background.pbs {
    background: url(../assets/images/nav/nav_button_blue_home.png) no-repeat;
    background-size: 100% 100%;
}

.nav_button_background.selected {
    background: url(../assets/images/nav/nav_button_green.png) no-repeat;
    background-size: 100% 100%;
}

.nav_button_container:last-child {
    margin: 0;
}

.nav_button_container:first-child {
    width: 15%;
}

.nav_button {
    position: absolute;
    top: 0;
    left: 12.5%;
    width: 75%;
    height: auto;
    margin: 0 auto;
}

.nav_button:last-child {
    margin: 0;
}

.nav_button.selected {
    background: url(../assets/images/nav/nav_button_green.png) no-repeat;
    background-size: 100% 100%;
}

.nav_button_icon.pbs {
    max-width: 60%;
    height: auto;
}

#background_pattern {

    background-size: 100% 100%;
    position: absolute;
    width: 100vw;
    height: 100vh;
    z-index: 0;
}

#top_content {
    width: 100%;
    max-width: 1440px;
    height: 800px;
    margin: 0 auto;
}

.shelf_wrapper_left {
    width: 100%;
    max-width: 1552px;
    margin: 0 auto;
    background: url(../assets/images/nav/shelf_left.png) repeat-y left;
}

.shelf_wrapper_right {
    width: 100%;
    margin: 0 auto;
    background: url(../assets/images/nav/shelf_right.png) repeat-y right;
}

#books {
    position: absolute;
    top: 0;
    margin: 0 auto;
    width: 100%;
    max-width: 1440px;
    height: 860px;
    z-index: 2;
    pointer-events: none;
}

#book_left {
    position: absolute;
    top: 0;
    left: 0;
    height: 100%;
    width: 120px;
    background: url(../assets/images/home/redbook.png) no-repeat 0;
    background-size: auto 100%;
}

#book_right {
    position: absolute;
    top: 0;
    right: 0;
    height: 100%;
    width: 150px;
    background: url(../assets/images/home/brownbook.png) no-repeat 100%;
    background-size: auto 100%;
}

@media (max-width:1020px) {

    .nav_button_icon {
        padding-top: 3px;
    }

    .nav_button_container {
        margin: 0;
    }
}

@media (max-width:900px) {

    #books {
        height: 410px;
    }

    #book_left {
        width: 70px;
    }

    #book_right {
        width: 90px;
    }

}

@media (max-width: 780px) {

    #books {
        height: 435px;
    }

    #books {
        display: none;
    }
}