html, body {
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
    background: radial-gradient(circle at top, #333 0, #111 45%, #050505 100%);
}

/* Center the book on screen */
#container {
    width: 100vw;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}

/* Book wrapper */
.flip-book {
    width: 100%;
    height: 100%;
    box-shadow: 0 30px 60px rgba(0, 0, 0, 0.7);
    border-radius: 10px;
    background-size: cover;
    background-position: center;
    position: relative;
}

/* Fake book shadow on the desk */
.flip-book::before {
    content: "";
    position: absolute;
    inset: 10px;
    border-radius: 12px;
    box-shadow:
        0 0 0 1px rgba(0,0,0,0.4),
        0 25px 40px rgba(0,0,0,0.6);
    pointer-events: none;
}

/* Page base */
.page {
    background-color: hsl(35, 55, 98);
    border: 1px solid hsl(35, 25, 75);
    overflow: hidden;
    box-sizing: border-box;
    border-radius: 6px;
    position: relative;
}

/* Paper grain + inner shadow near the spine */
.page::after {
    content: "";
    position: absolute;
    inset: 0;
    background:
        linear-gradient(to right,
            rgba(0,0,0,0.18) 0%,
            rgba(0,0,0,0.06) 8%,
            rgba(255,255,255,0) 18%,
            rgba(255,255,255,0) 82%,
            rgba(0,0,0,0.04) 94%,
            rgba(0,0,0,0.18) 100%
        ),
        repeating-linear-gradient(
            0deg,
            rgba(255,255,255,0.4) 0px,
            rgba(255,255,255,0.4) 1px,
            rgba(230,230,230,0.4) 2px,
            rgba(230,230,230,0.4) 3px
        );
    mix-blend-mode: multiply;
    pointer-events: none;
}

/* Left page (自動でクラス .--left が付与される) */
.page.--left {
    border-right: 0;
    box-shadow: inset -8px 0 28px -6px rgba(0, 0, 0, 0.35);
}

/* Right page */
.page.--right {
    border-left: 0;
    box-shadow: inset 8px 0 28px -6px rgba(0, 0, 0, 0.35);
}

/* Hard cover pages (density: hard or showCover:true) */
.page.hard {
    background-color: hsl(35, 45, 82);
    border-color: hsl(30, 25, 55);
    box-shadow:
        inset 0 0 35px rgba(0, 0, 0, 0.55),
        0 0 0 1px rgba(0,0,0,0.6);
}

/* Optional cover helpers (mostly for HTML mode, harmless for images) */
.page.page-cover {
    background-color: hsl(30, 45, 78);
    border-color: hsl(30, 25, 55);
}
.page.page-cover.page-cover-top {
    box-shadow:
        inset 0 0 40px rgba(36, 10, 3, 0.6),
        -4px 0 10px rgba(0, 0, 0, 0.5);
}
.page.page-cover.page-cover-bottom {
    box-shadow:
        inset 0 0 40px rgba(36, 10, 3, 0.6),
        10px 0 10px rgba(0, 0, 0, 0.6);
}

/* Make images always fill the page nicely */
.flip-book img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center;
    display: block;
}

/* ▼ 見開き画像コンテナ（2枚横並び） */
.page-spread {
    width: 100%;
    aspect-ratio: 2820 / 2250;  /* ← 比率を固定する核心 */
    overflow: hidden;
    position: relative;
}

/* ▼ 中の画像（左右ページ） */
.page-spread img {
    width: 50%;   /* 見開きなので半分 */
    height: 100%;
    object-fit: cover; /* 余白ゼロで比率維持 */
}