/* Mobile reader chrome floats above a fixed, centered book viewport. */
.bb-mobile-tools-toggle { display: none; }
@media (max-width: 768px) {
    .bb-shell .bb-top-bar { display: none; }
    .bb-shell.bb-paper-motion .bb-stage-wrap {
        position: absolute;
        inset: 0;
        width: 100%;
        height: 100%;
        margin: 0;
        padding: max(76px, env(safe-area-inset-top, 0px)) 0 max(76px, env(safe-area-inset-bottom, 0px));
    }
    .bb-shell .bb-stage-viewport { box-sizing: border-box; padding: 0; }
    .bb-mobile-tools-toggle {
        display: inline-flex;
        align-items: center;
        justify-content: center;
        gap: 8px;
        position: absolute;
        left: 50%;
        bottom: max(18px, env(safe-area-inset-bottom, 0px));
        transform: translateX(-50%);
        z-index: 80;
        min-width: 106px;
        min-height: 48px;
        padding: 10px 18px;
        border: 1px solid rgba(255,255,255,.8);
        border-radius: 999px;
        background: rgba(248,250,252,.88);
        color: #26323a;
        box-shadow: 0 6px 22px rgba(20,35,44,.15), inset 0 1px 0 #fff;
        -webkit-backdrop-filter: blur(22px) saturate(160%);
        backdrop-filter: blur(22px) saturate(160%);
        font: 500 13px/1.5 Tahoma,sans-serif;
        cursor: pointer;
        touch-action: manipulation;
    }
    .bb-mobile-tools-toggle[aria-expanded="true"] { background: rgba(225,233,239,.94); }
    .bb-shell .bb-catalog-navigation {
        position: absolute;
        left: 50%;
        right: auto;
        bottom: calc(max(18px, env(safe-area-inset-bottom, 0px)) + 60px);
        width: min(360px, calc(100% - 32px));
        box-sizing: border-box;
        padding: 10px;
        border: 1px solid rgba(255,255,255,.85);
        border-radius: 28px;
        background: rgba(245,248,251,.76);
        color: #26323a;
        box-shadow: 0 12px 38px rgba(20,35,44,.19), inset 0 1px 0 #fff;
        -webkit-backdrop-filter: blur(26px) saturate(165%);
        backdrop-filter: blur(26px) saturate(165%);
        opacity: 0;
        visibility: hidden;
        pointer-events: none;
        transform: translate(-50%, 14px) scale(.94);
        transform-origin: center bottom;
        transition: opacity .24s ease, transform .28s ease, visibility .24s;
        max-height: calc(100dvh - 150px);
        overflow: auto;
    }
    .bb-shell .bb-catalog-navigation.is-mobile-open:not(.is-hidden) {
        opacity: 1; visibility: visible; pointer-events: auto;
        transform: translate(-50%, 0) scale(1);
    }
    .bb-shell .bb-catalog-actions {
        justify-content: center;
        flex-wrap: wrap;
        gap: 4px;
        padding: 0;
        border: 0;
        background: transparent;
        box-shadow: none;
        backdrop-filter: none;
        -webkit-backdrop-filter: none;
        overflow: visible;
        color: #26323a;
    }
    .bb-shell .bb-catalog-navigation .bb-bottom-btn {
        width: 44px; min-width: 44px; height: 44px;
        border-radius: 16px;
        color: #26323a;
        font-size: 1rem;
    }
    .bb-shell .bb-catalog-navigation .bb-bottom-btn:hover,
    .bb-shell .bb-catalog-navigation .bb-bottom-btn:focus-visible { background: rgba(30,62,83,.1); }
    .bb-shell .bb-catalog-indicator,
    .bb-shell #bb-page-indicator,
    .bb-shell .bb-copyright { color: #40535e; }
    .bb-shell .bb-copyright { padding: 7px 4px 0; line-height: 1.6; }
    .bb-shell .bb-view-count { color: #40535e; min-height: 44px; }
    .bb-shell.bb-paper-motion .bb-mobile-page-btn {
        position: absolute;
        top: auto;
        bottom: max(20px, env(safe-area-inset-bottom, 0px));
        width: 44px; height: 44px;
        border-radius: 50%;
        color: #40535e;
        background: rgba(248,250,252,.72);
        border: 1px solid rgba(255,255,255,.8);
        box-shadow: 0 4px 14px rgba(20,35,44,.1);
    }
    .bb-mobile-tools-toggle:focus-visible { outline: 3px solid #186a9b; outline-offset: 3px; }
    .bb-shell .bb-thumbnails { margin-top: 8px; }
    .bb-shell .bb-desktop-zoom-btn { display: inline-flex; }
    .bb-shell:has(.bb-mobile-zoom-layer) .bb-mobile-tools-toggle { visibility: hidden; }
}
@media (max-width: 768px) and (prefers-reduced-motion: reduce) {
    .bb-shell .bb-catalog-navigation { transition: none; }
}