.grid {
    display: grid;
    gap: 40px;
    grid-template-columns: 1fr;
}

@media (min-width: 900px) {
    .grid {
        grid-template-columns: 1fr 1fr;
        align-items: center;
    }
}

/* =========================================================
       A) CSS-ONLY BOOK with Page-Flip on Hover/Click + Float
       ========================================================= */
.stage {
    perspective: 1600px;
    display: grid;
    place-items: center;
}

.book {
    position: relative;
    width: var(--book-w);
    height: var(--book-h);
    transform-style: preserve-3d;
    transform: rotateX(10deg) rotateY(-18deg) rotateZ(0.5deg) translateZ(0);
    transition: transform .6s cubic-bezier(.19, 1, .22, 1), filter .6s;
    filter: drop-shadow(var(--shadow));
    animation: float 6s ease-in-out infinite;
}

@keyframes float {

    0%,
    100% {
        transform: rotateX(10deg) rotateY(-18deg) translateY(0)
    }

    50% {
        transform: rotateX(12deg) rotateY(-16deg) translateY(-8px)
    }
}

/* pages block (right thickness) */
.pages {
    position: absolute;
    inset: 0;
    border-radius: 10px;
    background:
        repeating-linear-gradient(to right, #fbfbfb 0 2px, #ececec 2px 3px);
    transform: translateZ(calc(var(--book-d)/-2));
}

/* back cover */
.back {
    position: absolute;
    inset: 0;
    border-radius: 10px;
    background: #0f172a;
    /* dark back */
    transform: translateZ(calc(var(--book-d)/-2));
}

/* front cover as a hinged panel */
.cover {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    transform-origin: left center;
    transform: rotateY(-22deg) translateZ(calc(var(--book-d)/2));
    transition: transform .6s cubic-bezier(.19, 1, .22, 1);
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 6px 0 16px rgba(0, 0, 0, .35);
    will-change: transform;
}

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

/* book hover: open slightly + lift */
.book:hover {
    transform: rotateX(6deg) rotateY(-10deg) translateY(-4px);
}

.book:hover .cover {
    transform: rotateY(-8deg) translateZ(calc(var(--book-d)/2));
}

/* click to flip further (via a toggled class) */
.book.is-open .cover {
    transform: rotateY(-145deg) translateZ(calc(var(--book-d)/2));
}

/* subtle highlight sweep */
.book::after {
    content: "";
    position: absolute;
    inset: -10%;
    pointer-events: none;
    background: conic-gradient(from 210deg at 10% 10%, rgba(255, 255, 255, .15), transparent 25% 75%, rgba(255, 255, 255, .1));
    mix-blend-mode: screen;
    opacity: .0;
    transition: opacity .4s, transform .6s;
    transform: translateX(-10%);
}

.book:hover::after {
    opacity: .7;
    transform: translateX(0%);
}


/* =========================================================
       B) REAL 3D BOOK with Three.js (click to open/close)
       ========================================================= */
/* 3D Book Container */
#three-wrap {
    position: relative;
    height: 560px;
    border-radius: 18px;
    background: linear-gradient(to top, #f2f2f2 0%, #ffffff 100%);
    overflow: hidden;
    box-shadow: 73px 59px 152px rgba(-16, 21, 26, 1.15);
    display: initial;
    align-items: center;
    justify-content: center;
}

/* Canvas */
#three-book {
    height: 35rem;
    width: 20rem;
    display: flex;
    cursor: pointer;
}