#books {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 20px;
    padding: 20px;
}

.book {
    cursor: pointer;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    border-radius: 5px;
    overflow: hidden;
    position: relative;
    width: 150px;
    height: auto;
}

.book img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
}

.fullscreen-book-view {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.8);
    z-index: 1050;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow-y: auto;
}

.close-btn {
    position: fixed;
    top: 20px;
    right: 20px;
    background-color: #f00;
    color: #fff;
    border: none;
    border-radius: 50%;
    width: 50px;
    height: 50px;
    font-size: 22px;
    cursor: pointer;
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1100;
}

.loading-spinner {
    border: 16px solid #f3f3f3;
    border-top: 16px solid #3498db;
    border-radius: 50%;
    width: 120px;
    height: 120px;
    animation: spin 2s linear infinite;
    position: fixed;
    left: 50%;
    top: 50%;
    margin: -60px 0 0 -60px;
    z-index: 1500;
    display: none;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}