.logo {
    flex: 1;
    height: 100%;
    display: flex;
    align-items: center;
    font-size: 24px;
    color: #fff;
    max-width: calc(50% - 20px);
    margin: 0 auto;

}

@media screen and (max-width: 768px) {
    nav .logo {
        flex: none;
        width: auto;
        justify-content: center;
    }
}


.contenido-libro ul li {
    margin: 17px 0px;
}

.cuerpo-book p {
    margin-top: 8px;
}

section.content-book {
    text-align: center;
    background-color: #1b1a1a;
    padding-bottom: 17px;
}

.content-button {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.button {
    --green: #1BFD9C;
    font-size: 15px;
    padding: 0.7em 2.7em;
    letter-spacing: 0.06em;
    position: relative;
    font-family: inherit;
    border-radius: 0.6em;
    overflow: hidden;
    transition: all 0.3s;
    line-height: 1.4em;
    border: 2px solid var(--green);
    background: linear-gradient(to right, rgba(27, 253, 156, 0.1) 1%, transparent 40%, transparent 60%, rgba(27, 253, 156, 0.1) 100%);
    color: var(--green);
    box-shadow: inset 0 0 10px rgba(27, 253, 156, 0.4), 0 0 9px 3px rgba(27, 253, 156, 0.1);
    cursor: pointer;
}

.button:hover {
    color: #82ffc9;
    box-shadow: inset 0 0 10px rgba(27, 253, 156, 0.6), 0 0 9px 3px rgba(27, 253, 156, 0.2);
}

.button:before {
    content: "";
    position: absolute;
    left: -4em;
    width: 4em;
    height: 100%;
    top: 0;
    transition: transform .4s ease-in-out;
    background: linear-gradient(to right, transparent 1%, rgba(27, 253, 156, 0.1) 40%, rgba(27, 253, 156, 0.1) 60%, transparent 100%);
}

.button:hover:before {
    transform: translateX(15em);
}

.footer {

    background: #212121;
}