.customized-dark-blue-bg {
    background-color: #0a192f !important;
    padding: 0 !important;
}

.spacer {
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    background-color: #0d1e3d;
    color: #64ffda;
}

.scroll-wrapper {
    position: relative;
    height: 500vh; 
    background-color: #0a192f;
}

/* Background graphics */
.bg-graphic {
    position: absolute;
    pointer-events: none;
    z-index: 1;
}
.grid-pattern {
    top: 0; left: 0; width: 100%; height: 100%;
    background-image: linear-gradient(rgba(100, 255, 218, 0.03) 1px, transparent 1px),
                      linear-gradient(90deg, rgba(100, 255, 218, 0.03) 1px, transparent 1px);
    background-size: 40px 40px;
}


/* FIX: Repositioned Moving Line Track downwards & layered underneath content */
.scroll-progress-line-container {
    position: absolute;
    top: 72%; /* Tweak position down slightly to account for the larger cover footprints */
    left: 0;
    width: 95vw;
    height: 2px;
    background-color: rgba(255, 255, 255, 0.05); 
    z-index: 2; 
}

.moving-fill-line {
    width: 0%; 
    height: 100%;
    background: linear-gradient(90deg, #00a3e0, #64ffda);
    box-shadow: 0 0 8px #64ffda; 
    will-change: width;
}

.sticky-container {
    position: sticky;
    top: 0;
    height: 100vh;
    width: 95vw;
    display: flex;
    flex-direction: column;
    justify-content: center;
    overflow: hidden;
    z-index: 3;
}

.sticky-container h2 {
    font-size: 48px;
    color: #ffffff;
    text-align: center;
    margin: 0;
    position: absolute;
    top: 6%; /* Moved up slightly to allocate vertical headroom for larger covers */
    width: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    margin-top: 70px;
    margin-bottom: 20px;
}
@media (max-width: 580px) {
.sticky-container h2 {
    font-size: 28px;
    top: 8%;
    width: 98%;
    display: flex;
    flex-direction: column;
    align-items: center;
    margin-top: 60px;
}    
}
    

.title-line {
    display: block;
    width: 75px;
    height: 4px;
    background-color: #64ffda;
    margin-top: 15px;
    border-radius: 2px;
}

.books-timeline {
    display: flex;
    align-items: center;
    padding-left: 14vw; 
    width: max-content;
    will-change: transform;
    z-index: 5; 
    margin-top: 5vw;
}
@media (max-width: 580px) {
.books-timeline {
    margin-top: 100px;
}    
}
@media (max-width: 380px) {
.books-timeline {
    margin-top: 150px;
}    
}

.book-item {
    display: flex;
    flex-direction: row; 
    align-items: center;
    margin-right: 150px; /* Increased separation buffer space */
    width: 840px;        /* INCREASED: Broadened section box container for the larger cover layout */
}
.book-item:last-child {
    margin-right: 0 !important;
}
@media (max-width: 1600px) {
.book-item {
    width: 660px;
}
}
@media (max-width: 768px) {
.book-item {
    width: 87vw; 
    margin-right: 50px;
}
}

.book-cover {
    width: 360px;  /* INCREASED: Maximum size for prominent desktop displays */
    height: 500px; /* INCREASED: Aspect-ratio scaled height extension */
    box-shadow: 0 25px 50px rgba(0, 0, 0, 0.5);
    border-radius: 6px;
    flex-shrink: 0;
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.5s ease-out, transform 0.5s ease-out;
    border: 1px solid rgba(250, 250, 250, 0.1);
    background-color: #172a45;
}
@media (max-width: 1600px) {
.book-cover {
    width: 250px; /* Steps down smoothly for mid-size desktop configurations */
    height: 350px;
}    
}
@media (max-width: 768px) {
.book-cover {
    width: 180px; /* Keeps your optimized mobile sizes secure */
    height: 255px;
}    
}
@media (max-width: 580px) {
.book-cover {
    width: 140px; 
    height: 200px;
}    
}

.book-cover img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    border-radius: 4px;
}

/* FIX: Padding adaptation ensures descriptions float comfortably above the track alignment */
.book-desc-box {
    margin-left: 45px; /* Increased separation gap for clean structure breathing room */
    flex-grow: 1;
    opacity: 0;
    transform: translateY(30px);
    position: relative;
    padding-left: 20px;
    padding-bottom: 40px; 
    transition: opacity 0.5s ease-out, transform 0.5s ease-out;
}
@media (max-width: 580px) {
.book-desc-box {
    margin-left: 20px;
    padding-left: 12px;
}
}

.deco-accent-line {
    position: absolute;
    left: 0;
    top: 0;
    width: 2px;
    height: 0%;
    background: linear-gradient(to bottom, #64ffda, transparent);
    transition: height 0.7s cubic-bezier(0.25, 1, 0.5, 1);
}

.book-desc-box.active .deco-accent-line {
    height: 80%; 
}

.book-desc-box h3 {
    font-size: 1.55rem; /* Up-scaled title font to balance with the huge cover graphics */
    color: #ffffff;
    margin: 0 0 10px 0;
    line-height: 1.3;
}

.book-desc-box .size-tag {
    color: #64ffda;
    font-weight: bold;
    margin: 0 0 14px 0;
    font-size: 1rem;
    letter-spacing: 1px;
    display: inline-block;
}

.book-desc-box .details {
    color: #8892b0;
    font-size: 1rem;
    line-height: 1.4;
    margin: 0;
}

@media (max-width: 1600px) {
.book-desc-box h3 {
    font-size: 1.15rem;
    line-height: 1.22rem;
}    
.book-desc-box .details {
    font-size: 0.9rem;
    line-height: 1.2;
}    
}
@media (max-width: 580px) {
.book-desc-box h3 {
    font-size: 1.05rem;
    line-height: 1.25;
}    
.book-desc-box .details {
    font-size: 0.82rem;
    line-height: 1.2;
}    
}

@media (max-width: 480px) {
.book-desc-box h3 {
    font-size: 0.95rem;
    line-height: 1.15;
}    
.book-desc-box .details {
    font-size: 0.72rem;
    line-height: 1.1;
}    
	.book-desc-box .size-tag {
    color: #64ffda;
    font-weight: bold;
    margin: 0 0 7px 0;
    font-size: 0.9rem;
    letter-spacing: 1px;
    display: inline-block;
}

}

.book-cover.active, .book-desc-box.active {
    opacity: 1;
    transform: translateY(0);
}