.content-section {
    max-width: var(--container-max-width);
    margin: var(--spacing-xl) auto;
    padding: 0 var(--container-padding);
}

.version-selector {
    margin-bottom: var(--spacing-lg);
    text-align: right;
}

.version-selector select {
    padding: var(--spacing-sm) var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-size: var(--font-md);
    color: var(--text-color);
    background-color: var(--background-color);
}

.books-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: var(--spacing-lg);
}

.book-item {
    padding: var(--spacing-lg);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.book-item:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.book-item h2 {
    margin-bottom: var(--spacing-sm);
    color: var(--primary-color);
    font-size: var(--font-lg);
}

.book-description {
    color: var(--light-text);
    font-size: var(--font-sm);
    line-height: 1.5;
}

.loading-container {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1.5rem;
    z-index: 1000;
    background: rgba(var(--background-color-rgb), 0.95);
    padding: 2.5rem;
    border-radius: 12px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
    backdrop-filter: blur(8px);
}

.loading-spinner {
    position: relative;
    width: 40px;
    height: 60px;
}

.loading-spinner::before,
.loading-spinner::after {
    content: '';
    position: absolute;
    background: var(--primary-color);
    border-radius: 2px;
}

.loading-spinner::before {
    top: 0;
    left: 50%;
    width: 6px;
    height: 100%;
    transform: translateX(-50%);
    animation: pulseVertical 1.5s ease-in-out infinite;
}

.loading-spinner::after {
    top: 35%;
    left: 0;
    width: 100%;
    height: 6px;
    transform: translateY(-50%);
    animation: pulseHorizontal 1.5s ease-in-out infinite 0.2s;
}

.loading-text {
    color: var(--text-color);
    font-family: 'Cormorant Garamond', serif;
    font-size: 1.2rem;
    font-weight: 500;
    letter-spacing: 0.08em;
    text-align: center;
    opacity: 0.9;
    animation: fadeInOut 2s ease-in-out infinite;
}

@keyframes pulseVertical {
    0%, 100% {
        opacity: 0.3;
        transform: translateX(-50%) scaleY(0.9);
    }
    50% {
        opacity: 1;
        transform: translateX(-50%) scaleY(1);
    }
}

@keyframes pulseHorizontal {
    0%, 100% {
        opacity: 0.3;
        transform: translateY(-50%) scaleX(0.85);
    }
    50% {
        opacity: 1;
        transform: translateY(-50%) scaleX(1);
    }
}

@keyframes fadeInOut {
    0%, 100% {
        opacity: 0.6;
    }
    50% {
        opacity: 1;
    }
}

.error {
    text-align: center;
    color: var(--error-color);
    padding: var(--spacing-lg);
    background: var(--error-bg);
    border-radius: var(--radius-sm);
    margin: var(--spacing-lg) 0;
    font-size: var(--font-md);
    line-height: 1.6;
}