:root {
            --ink: #0e0d0b;
            --paper: #f4f0e8;
            --paper-dark: #e8e2d4;
            --red: #c0392b;
            --gold: #b8975a;
            --muted: #7a7060;
            --serif: 'Outfit', 'Inter', sans-serif;
            --mono: 'DM Mono', monospace;
        }
        body.dark-theme {
            --ink: #ffffff;
            --paper: #0a0a0a;
            --paper-dark: #141414;
            --muted: #b0aba1;
        }
        body.dark-theme .nav-bar {
            background: rgba(14, 13, 11, 0.7) !important;
            border-bottom: 1px solid rgba(244, 240, 232, 0.1) !important;
        }
        body.dark-theme .sidebar {
            background: #111 !important;
            border-right: 1px solid rgba(255, 255, 255, 0.1) !important;
        }
        body.dark-theme .nav-actions {
            background: rgba(17, 17, 17, 0.95) !important;
            border-top-color: rgba(255,255,255,0.1) !important;
        }
        
        /* Tema Estilo Planeta de Libros */
        body.planeta-theme {
            --ink: #333333;
            --paper: #ffffff;
            --paper-dark: #f5f5f5;
            --gold: #0f81e4; /* Planeta Blue as primary accent */
            --muted: #666666;
            --card-bg: #ffffff;
            --card-border: #e0e0e0;
            background-color: #ffffff !important;
            color: #333333 !important;
        }
        body.planeta-theme .nav-bar {
            background: #ffffff !important;
            border-bottom: 1px solid #e0e0e0 !important;
            box-shadow: 0 2px 10px rgba(0,0,0,0.05);
        }
        body.planeta-theme .nav-actions {
            background: #ffffff !important;
            border-top-color: #e0e0e0 !important;
        }
        body.planeta-theme .book-card {
            background: #ffffff !important;
            border: 1px solid #e0e0e0 !important;
            box-shadow: 0 4px 6px rgba(0,0,0,0.05) !important;
        }
        body.planeta-theme .book-card-title {
            color: #333333 !important;
        }
        body.planeta-theme .book-card-year, body.planeta-theme .author-label {
            color: #0f81e4 !important;
            font-weight: 600;
        }
        body.sepia-theme {
            --ink: #433422;
            --paper: #f4ecd8;
            --paper-dark: #e8deb8;
            --muted: #8c7b64;
            --gold: #a67c38;
            background-color: #f4ecd8 !important;
            color: #433422 !important;
        }
        /* Sunset Theme */
        body.sunset-theme {
            --ink: #4a2820;
            --paper: #fcece3;
            --paper-dark: #f0ddd1;
            --muted: #a67468;
            --gold: #d17a60;
            background-color: var(--paper) !important;
            color: var(--ink) !important;
        }
            body.dark-theme .nav-actions button, body.dark-theme .nav-actions .menu-toggle {
                color: #ddd;
            }
            .nav-actions button.active { color: var(--gold); }
            .hide-mobile { display: block !important; font-size: 0.55rem !important; margin-top: 2px; text-transform: capitalize; letter-spacing: normal; }
            .nav-actions button i, .nav-actions button svg { width: 22px; height: 22px; }
            
            .main-content { padding: 1.5rem 1rem 6rem 1rem; }
            h1 { font-size: 2.2rem; }
            h2 { font-size: 1.6rem; }
            h3 { font-size: 1.3rem; }