:root {
    --bg: #0a0c10;
    --bg-elevated: #12151c;
    --bg-card: #181c26;
    --bg-card-hover: #1e2330;
    --text: #eaedf3;
    --text-secondary: #9ca3b8;
    --text-dim: #6b7280;
    --accent: #4ade80;
    --accent-rgb: 74, 222, 128;
    --accent-hover: #22c55e;
    --accent-dim: rgba(74, 222, 128, 0.08);
    --purple: #818cf8;
    --purple-dim: rgba(129, 140, 248, 0.08);
    --amber: #fbbf24;
    --border: #1f2433;
    --border-hover: #2d3348;
    --radius: 14px;
    --radius-sm: 8px;
    --shadow: 0 8px 32px rgba(0,0,0,0.4);
    --shadow-sm: 0 2px 8px rgba(0,0,0,0.2);
    --transition: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

* { margin: 0; padding: 0; box-sizing: border-box; }
body {
    font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "Segoe UI", sans-serif;
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
}

/* ── Header ── */
.store-app { max-width: 1200px; margin: 0 auto; padding: 0 1.5rem; }
.store-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1.2rem 0;
    margin-bottom: 2rem;
    border-bottom: 1px solid var(--border);
}
.store-logo {
    display: flex;
    align-items: center;
    gap: 0.4rem;
    text-decoration: none;
    color: var(--text);
}
.logo-icon { font-size: 1.3rem; }
.logo-text { font-weight: 700; font-size: 1.05rem; }
.logo-sep { color: var(--text-dim); margin: 0 0.2rem; }
.logo-section { color: var(--accent); font-weight: 600; font-size: 1.05rem; }
.store-nav { display: flex; gap: 0.5rem; }
.nav-link {
    padding: 0.4rem 1rem;
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    transition: all var(--transition);
}
.nav-link:hover { color: var(--text); background: var(--bg-card); }
.nav-link.active { color: var(--accent); background: var(--accent-dim); }

/* ── Catalog ── */
.catalog-hero {
    text-align: center;
    padding: 2rem 0 3rem;
}
.catalog-hero h2 {
    font-size: 1.8rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    background: linear-gradient(135deg, var(--text) 0%, var(--accent) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}
.catalog-hero p { color: var(--text-secondary); font-size: 1rem; }

.catalog-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 1.5rem;
    padding-bottom: 2rem;
}

/* ── Book Card (Catalog) ── */
.book-card {
    background: var(--bg-card);
    border-radius: var(--radius);
    overflow: hidden;
    border: 1px solid var(--border);
    transition: all var(--transition);
    cursor: pointer;
    position: relative;
}
.book-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow);
    border-color: var(--border-hover);
    background: var(--bg-card-hover);
}
.book-card-cover {
    width: 100%;
    aspect-ratio: 2/3;
    object-fit: cover;
    display: block;
}
.book-card-cover-placeholder {
    width: 100%;
    aspect-ratio: 2/3;
    background: linear-gradient(135deg, var(--bg-elevated) 0%, var(--bg-card) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-dim);
    font-size: 2.5rem;
}
.book-card-body { padding: 1rem 1.2rem 1.2rem; }
.book-card-title {
    font-size: 1.05rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
    line-height: 1.35;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}
.book-card-author { color: var(--text-secondary); font-size: 0.85rem; margin-bottom: 0.6rem; }
.book-card-desc {
    color: var(--text-dim);
    font-size: 0.8rem;
    line-height: 1.5;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}
.book-card-bottom {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-top: 0.8rem;
    padding-top: 0.8rem;
    border-top: 1px solid var(--border);
}
.book-card-tags { display: flex; gap: 0.3rem; flex-wrap: wrap; flex: 1; }
.book-card-price {
    font-weight: 700;
    font-size: 1.05rem;
    color: var(--accent);
    white-space: nowrap;
    margin-left: 0.5rem;
}

/* ── Tags ── */
.tag {
    padding: 0.15rem 0.5rem;
    border-radius: 5px;
    font-size: 0.7rem;
    font-weight: 500;
    letter-spacing: 0.02em;
}
.tag-genre { background: var(--purple-dim); color: var(--purple); }
.tag-age { background: rgba(251, 191, 36, 0.08); color: var(--amber); }
.tag-keyword { background: var(--accent-dim); color: var(--accent); }

/* ── Book Detail Page ── */
.book-detail {
    display: grid;
    grid-template-columns: 320px 1fr;
    gap: 3rem;
    padding: 1rem 0 3rem;
}
.book-detail-left { position: sticky; top: 2rem; align-self: start; }
.book-detail-cover {
    width: 100%;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    display: block;
}

/* Price card */
.price-card {
    margin-top: 1.5rem;
    padding: 1.2rem;
    background: var(--bg-card);
    border-radius: var(--radius);
    border: 1px solid var(--border);
}
.price-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.5rem 0;
}
.price-row:not(:last-child) { border-bottom: 1px solid var(--border); }
.price-label { color: var(--text-secondary); font-size: 0.9rem; }
.price-value { font-weight: 700; font-size: 1.2rem; color: var(--accent); }
.price-value.audio { color: var(--purple); }

/* Right column */
.book-detail-right { padding-top: 0.5rem; }
.book-detail-title {
    font-size: 2.2rem;
    font-weight: 800;
    line-height: 1.15;
    margin-bottom: 0.4rem;
    letter-spacing: -0.02em;
}
.book-detail-author {
    font-size: 1.15rem;
    color: var(--text-secondary);
    margin-bottom: 1.2rem;
}
.book-detail-genres { display: flex; gap: 0.4rem; flex-wrap: wrap; margin-bottom: 1.2rem; }
.book-detail-desc {
    line-height: 1.75;
    margin-bottom: 1.5rem;
    color: var(--text);
    font-size: 0.95rem;
}
.book-detail-tags { display: flex; gap: 0.4rem; flex-wrap: wrap; margin-bottom: 1.5rem; }

/* Info pills */
.book-info-pills {
    display: flex;
    gap: 0.6rem;
    flex-wrap: wrap;
    margin-bottom: 2rem;
}
.info-pill {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    padding: 0.35rem 0.8rem;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 20px;
    font-size: 0.8rem;
    color: var(--text-secondary);
}
.info-pill .pill-icon { font-size: 0.85rem; }

/* Download section */
.download-section {
    padding: 1.5rem;
    background: var(--bg-elevated);
    border-radius: var(--radius);
    border: 1px solid var(--border);
}
.download-section h3 {
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--text-dim);
    margin-bottom: 1rem;
}
.download-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 0.6rem;
}
.dl-btn {
    display: flex;
    align-items: center;
    gap: 0.6rem;
    padding: 0.75rem 1rem;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text);
    text-decoration: none;
    font-size: 0.9rem;
    transition: all var(--transition);
    cursor: pointer;
}
.dl-btn:hover {
    background: var(--accent-dim);
    border-color: var(--accent);
    color: var(--accent);
}
.dl-btn .dl-icon { font-size: 1.3rem; }
.dl-btn .dl-info { display: flex; flex-direction: column; }
.dl-btn .dl-format { font-weight: 600; }
.dl-btn .dl-hint { font-size: 0.7rem; color: var(--text-dim); }

/* Back link */
.back-link {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.85rem;
    margin-bottom: 1.5rem;
    padding: 0.3rem 0;
    transition: color var(--transition);
}
.back-link:hover { color: var(--accent); }

/* ── Footer ── */
.store-footer {
    margin-top: 3rem;
    padding: 1.5rem 0;
    border-top: 1px solid var(--border);
    color: var(--text-dim);
    font-size: 0.8rem;
    text-align: center;
}
.footer-links {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
    margin-bottom: 0.8rem;
}
.footer-links a { color: var(--text-secondary); text-decoration: none; font-size: 0.8rem; }
.footer-links a:hover { color: var(--accent); }

/* ── Loading / Empty ── */
.loading {
    text-align: center;
    padding: 4rem 1rem;
    color: var(--text-dim);
    font-size: 0.95rem;
}
.empty-state {
    text-align: center;
    padding: 5rem 2rem;
}
.empty-state .empty-icon { font-size: 3rem; margin-bottom: 1rem; opacity: 0.5; }
.empty-state p { color: var(--text-dim); }

/* ── Responsive ── */
@media (max-width: 768px) {
    .store-app { padding: 0 1rem; }
    .store-header { flex-direction: column; gap: 0.8rem; align-items: flex-start; }
    .book-detail { grid-template-columns: 1fr; gap: 1.5rem; }
    .book-detail-left { position: static; max-width: 280px; margin: 0 auto; }
    .book-detail-title { font-size: 1.6rem; }
    .catalog-grid { grid-template-columns: repeat(auto-fill, minmax(160px, 1fr)); gap: 1rem; }
    .catalog-hero h2 { font-size: 1.4rem; }
    .download-grid { grid-template-columns: 1fr; }
}