body,
html {
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100%;
    background-color: #fff;
    /* Clean white background */
    font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
    color: #333;
}

.book-container {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    padding-top: 60px;
    box-sizing: border-box;
    overflow: hidden;
    background: #f9f9f9;
    /* Subtle difference for reader mode */
}

/* The actual flipbook container */
#flipbook {
    width: 100%;
    height: 100%;
    display: none;
}

.page {
    background-color: white;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.05);
    /* Softer shadow */
}

.page-content {
    width: 100%;
    height: 100%;
}

/* Controls */
.controls {
    position: fixed;
    bottom: 30px;
    left: 50%;
    transform: translateX(-50%);
    z-index: 100;
    background: #fff;
    padding: 10px 30px;
    border-radius: 50px;
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.1);
    display: flex;
    gap: 20px;
    align-items: center;
    border: 1px solid #eee;
}

.btn-control {
    background: none;
    border: none;
    cursor: pointer;
    font-size: 1.2rem;
    color: #000;
    transition: opacity 0.2s;
    padding: 5px;
}

.btn-control:hover {
    opacity: 0.6;
}

/* Loading Spinner */
#loading {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 1rem;
    color: #999;
    letter-spacing: 0.1em;
    text-transform: uppercase;
}

/* --- Catalog View Styles --- */
.catalog-view {
    padding: 120px 20px 60px;
    max-width: 1200px;
    margin: 0 auto;
    text-align: center;
}

.catalog-title {
    font-family: 'Courier New', Courier, monospace;
    /* Consistent with other pages */
    font-size: 2.5rem;
    margin-bottom: 60px;
    color: #000;
    font-weight: 400;
    text-transform: uppercase;
    letter-spacing: 2px;
}

.catalog-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    /* Wider cards */
    gap: 60px 40px;
    justify-content: center;
}

.book-card {
    background: transparent;
    border: none;
    padding: 0;
    cursor: pointer;
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
    transition: opacity 0.3s;
}

.book-card:hover {
    opacity: 0.7;
    transform: none;
    box-shadow: none;
}

.book-cover-placeholder,
.book-cover-img {
    width: 100%;
    aspect-ratio: 3/4;
    /* Standard book ratio */
    max-width: 250px;
    background-color: #f0f0f0;
    margin-bottom: 20px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
    /* Elegant shadow for cover */
    transition: box-shadow 0.3s;
    object-fit: cover;
}

.book-card:hover .book-cover-placeholder,
.book-card:hover .book-cover-img {
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.12);
}

.book-cover-placeholder {
    display: flex;
    align-items: center;
    justify-content: center;
    color: #999;
    font-family: 'Courier New', Courier, monospace;
    font-size: 0.9rem;
}

.book-title {
    font-size: 1.1rem;
    color: #000;
    margin: 10px 0 5px 0;
    font-weight: 400;
    letter-spacing: 0.05em;
    font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
}

.book-btn {
    background: transparent;
    color: #666;
    border: none;
    padding: 5px 0;
    cursor: pointer;
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.15em;
    border-bottom: 1px solid transparent;
    transition: all 0.2s;
}

.book-card:hover .book-btn {
    color: #000;
    border-bottom-color: #000;
}

/* --- Reader View Styles --- */
.back-btn {
    position: fixed;
    top: 100px;
    left: 40px;
    z-index: 100;
    background: transparent;
    border: none;
    padding: 10px;
    cursor: pointer;
    font-size: 0.9rem;
    color: #000;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
    transition: opacity 0.2s;
}

.back-btn:hover {
    opacity: 0.6;
    background: transparent;
}