/* Shared application shell for library, book, and chapter surfaces. */
.app-header {
    position: relative;
    z-index: 90;
    width: 100vw;
    max-width: none;
    margin-left: calc(50% - 50vw);
    padding: 0;
    border-bottom: 1px solid color-mix(in srgb, var(--border) 76%, transparent);
    background: color-mix(in srgb, var(--background) 88%, transparent);
    box-shadow: 0 1px 0 color-mix(in srgb, var(--card-bg) 76%, transparent);
    backdrop-filter: blur(18px) saturate(145%);
    -webkit-backdrop-filter: blur(18px) saturate(145%);
}

html {
    scroll-padding-top: var(--reader-navigation-offset, 0px);
}

[id] {
    scroll-margin-top: var(--reader-navigation-offset, 0px);
}

[data-navigation-behavior="sticky"] .app-header,
[data-navigation-behavior="auto-hide"] .app-header {
    position: sticky;
    top: 0;
    z-index: 90;
}

[data-navigation-behavior="auto-hide"] .app-header {
    transition: transform 220ms ease, opacity 220ms ease;
    will-change: transform, opacity;
}

[data-navigation-behavior="auto-hide"] .app-header.is-navigation-hidden {
    transform: translateY(-100%);
    opacity: 0;
    pointer-events: none;
}

[data-navigation-behavior="auto-hide"] .app-header:focus-within {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
}

@media (prefers-reduced-motion: reduce) {
    [data-navigation-behavior="auto-hide"] .app-header {
        transition: none;
    }
}

.app-nav {
    display: flex;
    align-items: center;
    gap: 18px;
    width: min(calc(100% - 40px), 1180px);
    min-width: 0;
    min-height: 68px;
    margin: 0 auto;
    padding: 8px 0;
}

.app-nav a,
.app-nav button {
    font: inherit;
}

.app-nav-brand {
    display: inline-flex;
    align-items: center;
    flex: 0 0 auto;
    gap: 10px;
    min-height: 44px;
    color: var(--text);
    font-size: .98rem;
    font-weight: 780;
    letter-spacing: -.025em;
    text-decoration: none;
}

.app-nav-brand-mark,
.breadcrumb-brand-mark {
    display: block;
    flex: 0 0 30px;
    width: 30px;
    height: 30px;
    margin: 0;
    object-fit: contain;
}

.app-nav-links,
.app-nav-actions {
    display: flex;
    align-items: center;
    min-width: 0;
}

.app-nav-links {
    align-self: stretch;
    flex: 1 1 auto;
    gap: 4px;
}

.app-nav-actions {
    flex: 0 0 auto;
    gap: 6px;
    margin-left: auto;
}

.app-nav-link,
.app-nav-action {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    min-height: 44px;
    padding: 0 12px;
    border: 0;
    border-radius: 10px;
    background: transparent;
    box-shadow: none;
    color: var(--text-secondary);
    font-size: .86rem;
    font-weight: 650;
    line-height: 1;
    text-decoration: none;
    white-space: nowrap;
    cursor: pointer;
    transition: color 160ms ease, background-color 160ms ease, box-shadow 160ms ease;
}

.app-nav-link:hover,
.app-nav-action:hover {
    background: var(--hover);
    color: var(--text);
    transform: none;
}

.app-nav-link.is-active {
    background: color-mix(in srgb, var(--button-bg) 11%, transparent);
    color: var(--button-bg);
}

.app-nav-link.is-loading,
.app-nav-link:disabled {
    cursor: progress;
    opacity: .76;
}

/* Keep AI-reading completion markers visible without loading the hub modal CSS. */
.ai-reading-chapter-badge {
    display: inline-flex;
    flex: 0 0 auto;
    align-items: center;
    gap: 5px;
    margin-left: auto;
    padding: 3px 8px;
    border-radius: 999px;
    color: var(--button-bg);
    background: color-mix(in srgb, var(--button-bg) 10%, transparent);
    font-size: .72rem;
    font-weight: 700;
    line-height: 1.2;
    white-space: nowrap;
}

.chapter-title-with-sync .ai-reading-chapter-badge { margin-left: 0; }
.chapter-link.active .ai-reading-chapter-badge,
.chapter-link:target .ai-reading-chapter-badge { color: inherit; background: color-mix(in srgb, white 18%, transparent); }

@media (max-width: 600px) {
    .ai-reading-chapter-badge {
        min-width: 24px;
        min-height: 22px;
        justify-content: center;
        gap: 0;
        padding: 3px 5px;
        font-size: .68rem;
    }
    .ai-reading-chapter-label { display: none; }
}

.app-nav-link i,
.app-nav-action i {
    color: currentColor;
    font-size: .98rem;
}

.app-nav .app-nav-theme {
    width: 44px;
    height: 44px;
    padding: 0;
    border-radius: 10px;
    background: transparent;
    color: var(--text-secondary);
    flex-direction: row;
}

.app-nav .app-nav-theme:hover {
    background: var(--hover);
    color: var(--text);
    transform: none;
}

.app-nav .app-nav-theme i {
    color: currentColor;
    font-size: .98rem;
}

.app-nav .app-nav-theme .app-nav-action-label {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

.app-nav .app-nav-action::before,
.app-nav .app-nav-locale::before {
    display: none;
}

.app-nav-locale {
    position: relative;
    display: inline-flex;
    align-items: center;
    min-height: 44px;
    padding: 0;
    border-radius: 10px;
}

.app-nav-locale .sr-only {
    position: absolute !important;
    width: 1px !important;
    min-width: 1px !important;
    max-width: 1px !important;
    height: 1px !important;
    min-height: 1px !important;
    max-height: 1px !important;
    padding: 0 !important;
    margin: -1px !important;
    overflow: hidden !important;
    clip: rect(0, 0, 0, 0) !important;
    clip-path: inset(50%) !important;
    white-space: nowrap !important;
    border: 0 !important;
}

.app-nav .app-nav-locale-toggle {
    width: 44px;
    height: 44px;
    min-height: 44px;
    padding: 0;
    gap: 0;
}

.app-nav-link:focus-visible,
.app-nav-action:focus-visible,
.app-nav-brand:focus-visible,
.app-nav-locale:focus-within {
    outline: 3px solid color-mix(in srgb, var(--button-bg) 34%, transparent);
    outline-offset: 2px;
}

.reader-toolbar.top-controls {
    position: fixed;
    top: 50%;
    right: 18px;
    z-index: 88;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-direction: column;
    gap: 4px;
    width: auto;
    margin: 0;
    padding: 5px;
    border: 1px solid var(--border);
    border-radius: 14px;
    background: color-mix(in srgb, var(--card-bg) 88%, transparent);
    box-shadow: var(--shadow-md);
    transform: translateY(-50%);
    transition: opacity 160ms ease, visibility 160ms ease, transform 160ms ease;
    backdrop-filter: blur(16px) saturate(140%);
    -webkit-backdrop-filter: blur(16px) saturate(140%);
}

@media (min-width: 769px) and (hover: hover) and (pointer: fine) {
    body.desktop-toolbar-auto-hide:not(.reader-drawer-open) .reader-toolbar.top-controls {
        right: var(--reader-edge-peek);
        opacity: .58;
        transform: translate(100%, -50%);
        transition-delay: 320ms;
        will-change: transform, opacity;
    }

    body.desktop-toolbar-auto-hide:not(.reader-drawer-open) .reader-toolbar.top-controls::before {
        content: '';
        position: absolute;
        top: 0;
        bottom: 0;
        left: -20px;
        width: 28px;
    }

    body.desktop-toolbar-auto-hide:not(.reader-drawer-open) .reader-toolbar.top-controls:hover,
    body.desktop-toolbar-auto-hide:not(.reader-drawer-open) .reader-toolbar.top-controls:focus-within {
        opacity: 1;
        transform: translate(0, -50%);
        transition-delay: 0ms;
    }
}

body.reader-drawer-open .reader-toolbar.top-controls {
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transform: translate(10px, -50%);
}

@media (prefers-reduced-motion: reduce) {
    body.desktop-toolbar-auto-hide .reader-toolbar.top-controls {
        transition: none;
    }
}

.reader-toolbar.top-controls .control-btn {
    position: relative;
    width: 42px;
    height: 42px;
    min-width: 42px;
    padding: 0;
    border-radius: 10px;
    background: transparent;
    box-shadow: none;
    color: var(--text-secondary);
    flex-direction: row;
    gap: 0;
}

.reader-toolbar.top-controls .control-btn::after {
    content: attr(aria-label);
    position: absolute;
    top: 50%;
    right: calc(100% + 10px);
    z-index: 2;
    width: max-content;
    max-width: 180px;
    padding: 7px 9px;
    border: 1px solid var(--border);
    border-radius: 8px;
    background: var(--card-bg);
    box-shadow: var(--shadow-sm);
    color: var(--text);
    font-size: .76rem;
    font-weight: 600;
    line-height: 1.2;
    opacity: 0;
    pointer-events: none;
    transform: translate(4px, -50%);
    transition: opacity 140ms ease, transform 140ms ease;
}

.reader-toolbar.top-controls .control-btn:hover::after,
.reader-toolbar.top-controls .control-btn:focus-visible::after {
    opacity: 1;
    transform: translate(0, -50%);
}

.reader-toolbar.top-controls .control-btn:hover {
    background: var(--hover);
    color: var(--text);
    transform: none;
}

.reader-toolbar.top-controls .control-btn:disabled,
.reader-toolbar.top-controls .control-btn:disabled:hover {
    background: transparent;
    color: var(--text-muted);
    opacity: 0.42;
    cursor: not-allowed;
}

.reader-toolbar.top-controls .control-btn:disabled::after {
    display: none;
}

.reader-toolbar.top-controls .control-name {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* Global floating action: only reveal scroll-to-top after meaningful scrolling. */
.reading-controls {
    gap: 0;
}

.reading-controls #scrollToTopBtn {
    width: 46px;
    height: 46px;
    border: 1px solid color-mix(in srgb, var(--button-bg) 22%, var(--border));
    border-radius: 14px;
    background: color-mix(in srgb, var(--card-bg) 94%, var(--button-bg));
    box-shadow: var(--shadow-md);
    color: var(--button-bg);
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transform: translateY(10px);
    transition: opacity 160ms ease, visibility 160ms ease, transform 160ms ease, background-color 160ms ease, color 160ms ease;
}

.reading-controls #scrollToTopBtn.is-visible {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    transform: translateY(0);
}

.reading-controls #scrollToTopBtn:hover {
    background: var(--button-bg);
    color: var(--button-text);
    transform: translateY(-2px);
}

.reading-controls #scrollToTopBtn .control-name {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

@media (max-width: 940px) {
    .app-nav {
        gap: 10px;
    }

    .app-nav-brand span,
    .app-nav-action-label,
    .app-nav #adminMenu span,
    .app-nav #accountMenu span {
        display: none;
    }

    .app-nav-action,
    .app-nav .app-nav-theme,
    .app-nav #adminMenu,
    .app-nav #accountMenu {
        width: 44px;
        padding: 0;
    }
}

@media (max-width: 768px) {
    .app-header {
        position: relative;
    }

    .app-nav {
        flex-wrap: wrap;
        gap: 6px 10px;
        width: 100%;
        padding: 8px 12px 7px;
    }

    .app-nav-brand {
        min-height: 44px;
    }

    .app-nav-brand-mark,
    .breadcrumb-brand-mark {
        flex-basis: 27px;
        width: 27px;
        height: 27px;
    }

    .app-nav-actions {
        order: 2;
    }

    .app-nav-links {
        order: 3;
        flex: 1 1 100%;
        width: 100%;
        padding-top: 6px;
        overflow-x: auto;
        border-top: 1px solid var(--border);
        scrollbar-width: none;
    }

    .app-nav-links::-webkit-scrollbar {
        display: none;
    }

    .app-nav-link {
        flex: 0 0 auto;
        min-height: 44px;
        padding: 0 10px;
    }

    .reader-toolbar.top-controls,
    .reading-controls {
        display: none;
    }
}