body {
    font-family: 'Open Sans', sans-serif; 
    text-align: center;
    padding-top: 2rem;
    background: url('bg.jpg') no-repeat center center;
    background-size: cover;
    background-attachment: fixed;
    color: white;

} 

h1 {
    font-size: 2.2rem;
}

h2 {
    font-size: 1.7rem;
}

h3 {
    font-size: 1.4rem;
}

.book_cont {
    text-align: center;
}
h4 {
    font-size: 1.1rem;
}

.buy_cont {
    margin: 3rem 0;
}

a {
    
    text-decoration: none;
}

.slogan-glowny {
    color: white;
    font-size: 2rem;
}

.slogan-glowny span {
    color: #82bbcf;
    font-size: 3rem;
}

body img {
    max-width: 100%; 
    max-height: 480px;
    width: auto;
    height: auto;
}

.social_link {
    font-size: 2rem;
}

.about_author {
    background: #216282;
    margin-bottom: 1rem;
    padding: 1rem 2rem 1rem 1rem;
    color: white;
}

.about_author h4 {
    font-size: 1.1rem;
}

.button_buy {
    background: #990D0B;
    color: white;
    padding: 0.7rem 2rem;
    text-decoration: none;
    
}

.button_buy:hover {
    text-decoration: none;
    color: #990D0B;
    background: white;
    
}

.overlay {
    background: #1b2134;
    opacity: 0.8;
    position: fixed;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
}

.buy_cont strong {
    font-size: 1.5rem;
}

.container {
    position: relative;
    z-index: 2;
    color: white;
}

.book_title {
    color: #82bbcf;
    margin-bottom:0rem;
}

.kuba {
    float: left;
    width: 180px;
    height: auto;
    margin-right: 1rem;
    margin-bottom: 0.5rem;
}

.author {
    margin-bottom: 2.5rem;
    font-size: 1.3rem;
    color: white;
    margin-top: .5rem;
}

@media all and (max-width: 767px) {
    body, html {
        font-size: 13px;
    }
        .slogan-glowny {
            
            font-size: 1rem;
        }
        
        .slogan-glowny span {
           
            font-size: 2rem;
        }
    
    .book_title {
        margin-top: 1.5rem;
    }
}

@media all and (max-width: 480px) {
    .kuba {
        float: none;
        margin: 1rem auto;
    }
}