.imagen-portada {
    width: 100%;
}
.imagen-portada img {
    width: 50%;
    display: block;
    margin: auto;
}
.titulo-libro {
    width: 100%;
    margin-top: 15px;
    margin-bottom: 15px;
    padding: 0px 10px;
    text-align: center;
    font-weight: bold;
}

.nav_search {
    float:left; 
    width: 30%; 
    padding-top: 10px;
}

.top_nav .form-group .input-group {
    margin-bottom: 0;
}

.botones {
    background: #2A3F54 !important;
    color: #FFF !important;
}

.botones:hover {
    background: #2A3F54 !important;
    color: #FFF !important;
    cursor: pointer;
}

@media (max-width: 510px) {
    .nav_search {
        width: 70%;
    }
}