/* ─── CSS Variables ──────────────────────────────────────────────── */
:root {
    --bg-color: #0e0e12;
    --bg-gradient: radial-gradient(ellipse at 50% 0%, #1a1a2e 0%, #0e0e12 65%);
    --text-color: #e8e4dc;
    --text-muted: rgba(232,228,220,.45);
    --accent-color: #8e8a7d;
    --accent-glow: rgba(142,138,125,.18);
    --ui-bg: rgba(18,18,22,.82);
    --ui-bg-solid: #141418;
    --border-color: rgba(255,255,255,.08);
    --border-light: rgba(255,255,255,.04);
    --shadow-book: 0 32px 80px rgba(0,0,0,.75), 0 8px 24px rgba(0,0,0,.5), 0 0 0 1px rgba(255,255,255,.04);
    --shadow-nav: 0 8px 40px rgba(0,0,0,.5), 0 1px 0 rgba(255,255,255,.06) inset;
    --shadow-sm: 0 4px 16px rgba(0,0,0,.3);
    --bg-image: none;
    --bg-overlay: rgba(0,0,0,.55);
    --toc-width: 300px;
}

[data-theme="light"] {
    --bg-color: #ede8e0;
    --bg-gradient: radial-gradient(ellipse at 50% 0%, #f5f0e8 0%, #e6dfd4 65%);
    --text-color: #1a1814;
    --text-muted: rgba(26,24,20,.4);
    --accent-color: #6b5e4e;
    --accent-glow: rgba(107,94,78,.12);
    --ui-bg: rgba(255,252,248,.88);
    --ui-bg-solid: #faf7f3;
    --border-color: rgba(0,0,0,.1);
    --border-light: rgba(0,0,0,.05);
    --shadow-book: 0 32px 80px rgba(0,0,0,.2), 0 8px 24px rgba(0,0,0,.12);
    --shadow-nav: 0 8px 40px rgba(0,0,0,.12), 0 1px 0 rgba(255,255,255,.8) inset;
    --shadow-sm: 0 4px 16px rgba(0,0,0,.1);
}

/* ─── Base ───────────────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; }

body {
    margin: 0;
    background: var(--bg-gradient);
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: 'Optima','Didot','Georgia',serif;
    height: 100vh;
    height: 100svh;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    align-items: center;
    transition: background-color 0.4s ease, color 0.4s ease;
}

a { color: var(--accent-color); text-decoration: none; }

/* ─── Artist Background Image ───────────────────────────────────── */
body.bg-image {
    background-image: var(--bg-image);
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
}

body.bg-image::before {
    content: '';
    position: fixed;
    inset: 0;
    background: var(--bg-overlay);
    z-index: 0;
    pointer-events: none;
}

/* ─── Loading Overlay ────────────────────────────────────────────── */
#loading-overlay {
    position: fixed;
    inset: 0;
    background: var(--bg-color);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 20px;
    z-index: 9999;
    transition: opacity 0.6s ease;
}

#loading-overlay.hidden {
    opacity: 0;
    pointer-events: none;
}

.loading-spinner {
    width: 40px;
    height: 40px;
    border: 2px solid var(--border-color);
    border-top-color: var(--accent-color);
    border-radius: 50%;
    animation: spin 1s cubic-bezier(.45,.05,.55,.95) infinite;
}

.loading-label {
    font-size: .6rem;
    letter-spacing: 5px;
    text-transform: uppercase;
    color: var(--text-muted);
    animation: pulse 1.6s ease-in-out infinite;
}

@keyframes spin { to { transform: rotate(360deg); } }
@keyframes pulse { 0%,100% { opacity:.3 } 50% { opacity:.8 } }

/* ─── TOC Backdrop ───────────────────────────────────────────────── */
#toc-backdrop {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,.55);
    backdrop-filter: blur(4px);
    -webkit-backdrop-filter: blur(4px);
    z-index: 1999;
    cursor: pointer;
    animation: fadeIn .25s ease;
}

#toc-backdrop.open { display: block; }
@keyframes fadeIn { from { opacity: 0 } to { opacity: 1 } }

/* ─── TOC Drawer ─────────────────────────────────────────────────── */
#toc-drawer {
    position: fixed;
    left: 0;
    top: 0;
    height: 100%;
    width: var(--toc-width);
    background: var(--ui-bg);
    backdrop-filter: blur(40px) saturate(1.4);
    -webkit-backdrop-filter: blur(40px) saturate(1.4);
    border-right: 1px solid var(--border-color);
    transform: translateX(-100%);
    transition: transform 0.32s cubic-bezier(.4,0,.2,1);
    z-index: 2000;
    overflow-y: auto;
    overflow-x: hidden;
    display: flex;
    flex-direction: column;
}

#toc-drawer.open { transform: translateX(0); }

#toc-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 24px 18px 16px;
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    background: var(--ui-bg);
    backdrop-filter: blur(40px);
    -webkit-backdrop-filter: blur(40px);
    z-index: 1;
}

#toc-title {
    font-size: .6rem;
    letter-spacing: 5px;
    text-transform: uppercase;
    color: var(--text-muted);
}

#toc-close {
    background: rgba(128,128,128,.12);
    border: none;
    border-radius: 50%;
    width: 28px;
    height: 28px;
    color: var(--text-color);
    cursor: pointer;
    opacity: .6;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0;
    transition: opacity 0.2s, background 0.2s;
}
#toc-close:hover { opacity: 1; background: rgba(128,128,128,.2); }
#toc-close svg { width: 16px; height: 16px; fill: currentColor; }

#toc-list { flex: 1; padding: 6px 0 40px; }

.toc-section-label {
    font-size: .55rem;
    letter-spacing: 4px;
    text-transform: uppercase;
    color: var(--text-muted);
    padding: 20px 18px 6px;
}

.toc-item {
    display: flex;
    align-items: center;
    gap: 12px;
    width: 100%;
    padding: 8px 18px;
    background: none;
    border: none;
    color: var(--text-color);
    cursor: pointer;
    text-align: left;
    font-family: inherit;
    font-size: .78rem;
    letter-spacing: .5px;
    transition: background 0.15s ease;
    border-left: 2px solid transparent;
}

.toc-item:hover { background: rgba(128,128,128,.08); }
.toc-item.active {
    background: var(--accent-glow);
    border-left-color: var(--accent-color);
}

.toc-thumb {
    width: 36px;
    height: 48px;
    object-fit: cover;
    border-radius: 3px;
    flex-shrink: 0;
    background: var(--border-color);
    box-shadow: var(--shadow-sm);
}

.toc-item-title {
    flex: 1;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    line-height: 1.4;
}

.toc-page-num {
    font-size: .6rem;
    color: var(--text-muted);
    flex-shrink: 0;
}

/* ─── Viewport & Book ────────────────────────────────────────────── */
#viewport {
    position: relative;
    z-index: 1;
    width: 100%;
    height: calc(100vh - 116px);
    height: calc(100svh - 116px);
    margin-top: 16px;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow: hidden;
    touch-action: none;
    cursor: grab;
}

#viewport:active { cursor: grabbing; }

/* El gesto táctil debe entregarse a JS aunque el dedo toque la obra */
#book-wrapper, #art-book, .page { touch-action: none; }

#book-wrapper {
    transform-origin: center center;
    position: relative;
    will-change: transform;
    filter: drop-shadow(0 40px 60px rgba(0,0,0,.6));
    /* sin transición por defecto: el pinch/paneo siguen al dedo al instante */
}

#book-wrapper.zoom-transition {
    transition: transform 0.28s cubic-bezier(.4,0,.2,1);
}

.page {
    background-size: contain;
    background-repeat: no-repeat;
    background-position: center;
    background-color: #1c1c1c;
}

[data-theme="light"] .page { background-color: #f8f5f0; }

/* ─── Navigation Bar ─────────────────────────────────────────────── */
.nav-bar {
    position: fixed;
    bottom: 24px;
    width: calc(100% - 64px);
    max-width: 960px;
    background: var(--ui-bg);
    backdrop-filter: blur(40px) saturate(1.6);
    -webkit-backdrop-filter: blur(40px) saturate(1.6);
    border: 1px solid var(--border-color);
    border-top: 1px solid rgba(255,255,255,.1);
    border-radius: 20px;
    padding: 10px 28px;
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    align-items: center;
    box-shadow: var(--shadow-nav);
    z-index: 1000;
}

/* subtle accent glow under nav bar */
.nav-bar::after {
    content: '';
    position: absolute;
    bottom: -1px;
    left: 20%;
    right: 20%;
    height: 1px;
    background: linear-gradient(90deg, transparent, var(--accent-color), transparent);
    opacity: .35;
    border-radius: 1px;
}

/* ─── Nav Left — Artist + Instagram ─────────────────────────────── */
.nav-left {
    display: flex;
    align-items: center;
    gap: 8px;
    overflow: hidden;
}

#instagram-link {
    display: flex;
    align-items: center;
    gap: 7px;
    color: var(--accent-color);
    font-size: .68rem;
    letter-spacing: 2.5px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    max-width: 220px;
    opacity: .8;
    transition: opacity .2s;
}
#instagram-link:hover { opacity: 1; }

#instagram-icon {
    width: 15px;
    height: 15px;
    fill: currentColor;
    flex-shrink: 0;
}

#nav-artist-name {
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    text-transform: uppercase;
}

/* ─── Nav Center — Page Flip Controls ───────────────────────────── */
.nav-center {
    display: flex;
    align-items: center;
    gap: 6px;
}

#prev-btn, #next-btn {
    background: rgba(128,128,128,.1);
    border: 1px solid var(--border-color);
    border-radius: 50%;
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-color);
    cursor: pointer;
    opacity: .8;
    transition: background .2s ease, opacity .2s ease, transform .2s ease, border-color .2s;
    padding: 0;
    font-family: inherit;
}
#prev-btn:hover, #next-btn:hover {
    opacity: 1;
    background: rgba(128,128,128,.2);
    border-color: var(--accent-color);
    transform: scale(1.08);
}
#prev-btn svg, #next-btn svg { width: 18px; height: 18px; fill: currentColor; }

.page-counter {
    font-size: .72rem;
    letter-spacing: 3px;
    min-width: 90px;
    text-align: center;
    color: var(--text-muted);
    font-variant-numeric: tabular-nums;
}

/* ─── Nav Right — Tools ──────────────────────────────────────────── */
.nav-right {
    display: flex;
    justify-content: flex-end;
    align-items: center;
    gap: 4px;
}

.zoom-group {
    display: flex;
    align-items: center;
    gap: 6px;
    margin-right: 6px;
}

/* Tool buttons */
button.tool-btn, .download-btn {
    background: none;
    border: none;
    border-radius: 8px;
    width: 34px;
    height: 34px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-color);
    cursor: pointer;
    opacity: .55;
    transition: opacity .2s ease, background .2s ease, transform .2s ease;
    padding: 0;
    font-family: inherit;
}

button.tool-btn:hover, .download-btn:hover {
    opacity: 1;
    background: rgba(128,128,128,.12);
    transform: scale(1.08);
}

button.tool-btn svg, .download-btn svg { width: 18px; height: 18px; fill: currentColor; }

/* TOC toggle inherits tool-btn styles */
#toc-toggle {
    background: none;
    border: none;
    border-radius: 8px;
    width: 34px;
    height: 34px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-color);
    cursor: pointer;
    opacity: .55;
    transition: opacity .2s ease, background .2s ease, transform .2s ease;
    padding: 0;
}
#toc-toggle:hover { transform: scale(1.08); }
#toc-toggle:hover { opacity: 1; background: rgba(128,128,128,.12); }
#toc-toggle svg { width: 18px; height: 18px; fill: currentColor; }

#muteBtn, #themeBtn {
    background: none;
    border: none;
    border-radius: 8px;
    width: 34px;
    height: 34px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-color);
    cursor: pointer;
    opacity: .55;
    transition: opacity .2s ease, background .2s ease, transform .2s ease;
    padding: 0;
    font-family: inherit;
}
#muteBtn:hover, #themeBtn:hover {
    opacity: 1;
    background: rgba(128,128,128,.12);
    transform: scale(1.08);
}
#muteBtn svg, #themeBtn svg { width: 18px; height: 18px; fill: currentColor; }

input[type=range] {
    width: 80px;
    accent-color: var(--accent-color);
    cursor: pointer;
    opacity: .6;
    transition: opacity .2s;
}
input[type=range]:hover { opacity: 1; }

/* ─── Mobile ─────────────────────────────────────────────────────── */
@media (max-width: 768px) {
    #viewport {
        height: calc(100svh - 168px);
        margin-top: 10px;
    }

    .nav-bar {
        bottom: calc(10px + env(safe-area-inset-bottom));
        width: calc(100% - 28px);
        padding: 10px 14px;
        border-radius: 18px;
        grid-template-columns: 1fr;
        gap: 10px;
        justify-items: center;
    }

    /* Cada fila ocupa todo el ancho y se centra: distribución vertical pareja */
    .nav-left, .nav-center, .nav-right {
        width: 100%;
        justify-content: center;
        align-items: center;
    }

    .nav-left {
        order: -1;
        font-size: .6rem;
        letter-spacing: 1.5px;
    }

    #instagram-link { max-width: 220px; font-size: .62rem; }

    .zoom-group { display: none; }
    .nav-center { gap: 16px; }
    .nav-right { gap: 14px; }

    /* Sin círculo decorativo: solo la flecha */
    #prev-btn, #next-btn {
        width: 40px;
        height: 40px;
        background: none;
        border: none;
        border-radius: 0;
    }
    #prev-btn:hover, #next-btn:hover {
        background: none;
        border: none;
        transform: none;
    }
    #prev-btn svg, #next-btn svg { width: 24px; height: 24px; }

    /* Iconos de la fila inferior, todos al mismo tamaño y centrados */
    #toc-toggle, #muteBtn, #themeBtn, .download-btn {
        width: 38px;
        height: 38px;
    }
    #toc-toggle svg, #muteBtn svg, #themeBtn svg, .download-btn svg {
        width: 19px;
        height: 19px;
    }

    #toc-drawer { width: min(var(--toc-width), 85vw); }
}

/* ─── Scrollbar ──────────────────────────────────────────────────── */
#toc-drawer::-webkit-scrollbar { width: 4px; }
#toc-drawer::-webkit-scrollbar-track { background: transparent; }
#toc-drawer::-webkit-scrollbar-thumb { background: var(--border-color); border-radius: 2px; }