:root {
            --bg: #f4f5f7;
            --card-bg: #ffffff;
            --text: #1a1a2e;
            --text-secondary: #6b7280;
            --text-muted: #9ca3af;
            --border: #e5e7eb;
            --accent: #2563eb;
            --accent-hover: #1d4ed8;
            --accent-light: #eff6ff;
            --danger: #ef4444;
            --danger-light: #fef2f2;
            --success: #10b981;
            --success-light: #ecfdf5;
            --warning: #f59e0b;
            --warning-light: #fffbeb;
            --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.04);
            --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.06);
            --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.09);
            --radius-sm: 6px;
            --radius: 10px;
            --radius-lg: 14px;
            --transition: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
            --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
            --font-mono: 'SF Mono', 'JetBrains Mono', 'Fira Code', 'Consolas', 'Monaco', 'Courier New', monospace;
            --footer-bg: #ffffff;
            --footer-border: #e5e7eb;
            --nav-link-color: #4b5563;
            --breadcrumb-color: #6b7280;
        }
        [data-theme="dark"] {
            --bg: #111827;
            --card-bg: #1f2937;
            --text: #f1f5f9;
            --text-secondary: #9ca3af;
            --text-muted: #6b7280;
            --border: #374151;
            --accent: #3b82f6;
            --accent-hover: #60a5fa;
            --accent-light: #1e3a5f;
            --danger: #f87171;
            --danger-light: #3b1a1a;
            --success: #34d399;
            --success-light: #0f2f24;
            --warning: #fbbf24;
            --warning-light: #2d2410;
            --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
            --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.35);
            --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.45);
            --footer-bg: #1f2937;
            --footer-border: #374151;
            --nav-link-color: #d1d5db;
            --breadcrumb-color: #9ca3af;
        }
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }
        body {
            font-family: var(--font-sans);
            background: var(--bg);
            color: var(--text);
            line-height: 1.6;
            min-height: 100vh;
            transition: background 0.3s, color 0.3s;
            -webkit-font-smoothing: antialiased;
        }
        .header {
            background: var(--card-bg);
            border-bottom: 1px solid var(--border);
            position: sticky;
            top: 0;
            z-index: 100;
            backdrop-filter: blur(16px);
            -webkit-backdrop-filter: blur(16px);
            transition: all 0.3s;
        }
        [data-theme="dark"] .header {
            background: rgba(31, 41, 55, 0.88);
        }
        .header-inner {
            max-width: 1260px;
            margin: 0 auto;
            display: flex;
            align-items: center;
            gap: 24px;
            padding: 0 20px;
            height: 56px;
            flex-wrap: wrap;
        }
        .logo {
            display: flex;
            align-items: center;
            gap: 8px;
            font-weight: 700;
            font-size: 1.1rem;
            letter-spacing: -0.01em;
            color: var(--text);
            text-decoration: none;
            white-space: nowrap;
            margin-right: auto;
        }
        .logo-icon {
            width: 34px;
            height: 34px;
            border-radius: var(--radius-sm);
            background: linear-gradient(135deg, #2563eb, #6366f1);
            display: flex;
            align-items: center;
            justify-content: center;
            color: #fff;
            font-family: var(--font-mono);
            font-weight: 800;
            font-size: 0.75rem;
        }
        .nav-menu {
            display: flex;
            gap: 6px;
            align-items: center;
            list-style: none;
            flex-wrap: wrap;
        }
        .nav-menu li a {
            display: block;
            padding: 6px 14px;
            border-radius: 18px;
            font-size: 0.82rem;
            font-weight: 500;
            color: var(--nav-link-color);
            text-decoration: none;
            transition: all var(--transition);
            white-space: nowrap;
            border: 1px solid transparent;
        }
        .nav-menu li a:hover {
            background: var(--accent-light);
            color: var(--accent);
            border-color: var(--border);
        }
        .nav-menu li a.active {
            background: var(--accent);
            color: #fff;
            border-color: var(--accent);
            font-weight: 600;
        }
        .theme-toggle {
            width: 38px;
            height: 38px;
            border-radius: 50%;
            border: 1.5px solid var(--border);
            background: var(--card-bg);
            cursor: pointer;
            font-size: 1rem;
            display: flex;
            align-items: center;
            justify-content: center;
            transition: all var(--transition);
            color: var(--text);
            flex-shrink: 0;
            font-weight: 700;
            margin-left: 8px;
        }
        .theme-toggle:hover {
            border-color: var(--accent);
            box-shadow: var(--shadow-sm);
            transform: scale(1.04);
        }
        @media (max-width: 768px) {
            .header-inner {
                height: auto;
                padding: 10px 16px;
                flex-direction: column;
                gap: 8px;
                align-items: flex-start;
            }
            .nav-menu {
                overflow-x: auto;
                width: 100%;
                padding-bottom: 4px;
            }
            .theme-toggle {
                position: absolute;
                top: 10px;
                right: 16px;
            }
        }
        .breadcrumb {
            font-size: 0.82rem;
            color: var(--breadcrumb-color);
            padding: 0 0 8px 0;
            display: flex;
            align-items: center;
            gap: 6px;
            flex-wrap: wrap;
        }
        .breadcrumb a {
            color: var(--breadcrumb-color);
            text-decoration: none;
            transition: color 0.2s;
        }
        .breadcrumb a:hover {
            color: var(--accent);
            text-decoration: underline;
        }
        .breadcrumb .separator {
            user-select: none;
        }
        .breadcrumb .current {
            color: var(--text);
            font-weight: 600;
        }
        .container {
            max-width: 1260px;
            margin: 0 auto;
            padding: 20px 18px 40px;
            display: flex;
            flex-direction: column;
            gap: 20px;
        }
        .converter-grid {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 20px;
            align-items: start;
        }
        @media (max-width: 860px) {
            .converter-grid {
                grid-template-columns: 1fr;
            }
        }
        .card {
            background: var(--card-bg);
            border-radius: var(--radius-lg);
            padding: 20px 22px;
            border: 1px solid var(--border);
            box-shadow: var(--shadow-sm);
            transition: all var(--transition);
            display: flex;
            flex-direction: column;
            gap: 14px;
        }
        .card:hover {
            box-shadow: var(--shadow-md);
        }
        .card-header {
            display: flex;
            align-items: center;
            gap: 8px;
            font-weight: 700;
            font-size: 0.9rem;
            color: var(--text);
        }
        .card-header .icon-circle {
            width: 32px;
            height: 32px;
            border-radius: 50%;
            background: var(--accent-light);
            color: var(--accent);
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 0.85rem;
            flex-shrink: 0;
        }
        .card-label-sm {
            font-size: 0.7rem;
            font-weight: 600;
            text-transform: uppercase;
            letter-spacing: 0.05em;
            color: var(--text-secondary);
            margin-bottom: 2px;
        }
        textarea {
            width: 100%;
            padding: 12px 14px;
            border-radius: var(--radius);
            border: 1.5px solid var(--border);
            font-size: 0.88rem;
            font-family: var(--font-mono);
            background: var(--bg);
            color: var(--text);
            resize: vertical;
            outline: none;
            transition: all var(--transition);
            line-height: 1.5;
            min-height: 100px;
        }
        textarea:focus {
            border-color: var(--accent);
            box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
        }
        .output-area {
            position: relative;
            background: var(--bg);
            border-radius: var(--radius);
            border: 1.5px solid var(--border);
            padding: 12px 40px 12px 14px;
            font-family: var(--font-mono);
            font-size: 0.85rem;
            color: var(--text);
            min-height: 56px;
            max-height: 240px;
            overflow-y: auto;
            word-break: break-all;
            line-height: 1.6;
            white-space: pre-wrap;
            transition: all var(--transition);
        }
        .output-area.empty {
            color: var(--text-muted);
            font-style: italic;
            display: flex;
            align-items: center;
        }
        .output-area.error {
            color: var(--danger);
            border-color: var(--danger);
            background: var(--danger-light);
        }
        .copy-btn {
            position: absolute;
            top: 8px;
            right: 8px;
            padding: 5px 10px;
            border-radius: 14px;
            border: 1px solid var(--border);
            background: var(--card-bg);
            color: var(--text-secondary);
            font-size: 0.68rem;
            font-weight: 600;
            cursor: pointer;
            transition: all var(--transition);
            white-space: nowrap;
            font-family: var(--font-sans);
            z-index: 2;
        }
        .copy-btn:hover {
            border-color: var(--accent);
            color: var(--accent);
            box-shadow: var(--shadow-sm);
        }
        .copy-btn.copied {
            background: var(--success);
            color: #fff;
            border-color: var(--success);
        }
        .options-row {
            display: flex;
            flex-wrap: wrap;
            gap: 8px;
            align-items: center;
        }
        .option-group {
            display: flex;
            gap: 3px;
            align-items: center;
            background: var(--bg);
            border-radius: 20px;
            padding: 3px;
            border: 1px solid var(--border);
            flex-wrap: wrap;
        }
        .option-btn {
            padding: 5px 11px;
            border-radius: 17px;
            font-size: 0.7rem;
            font-weight: 600;
            cursor: pointer;
            border: none;
            background: transparent;
            color: var(--text-secondary);
            transition: all var(--transition);
            white-space: nowrap;
            font-family: var(--font-sans);
        }
        .option-btn:hover {
            color: var(--accent);
        }
        .option-btn.active {
            background: var(--accent);
            color: #fff;
            box-shadow: var(--shadow-sm);
        }
        .example-row {
            display: flex;
            flex-wrap: wrap;
            gap: 6px;
            align-items: center;
        }
        .example-chip {
            padding: 4px 10px;
            border-radius: 14px;
            font-size: 0.68rem;
            font-weight: 500;
            cursor: pointer;
            border: 1px solid var(--border);
            background: var(--card-bg);
            color: var(--text-secondary);
            transition: all var(--transition);
            white-space: nowrap;
            font-family: var(--font-sans);
        }
        .example-chip:hover {
            border-color: var(--accent);
            color: var(--accent);
            background: var(--accent-light);
        }
        .stat-row {
            display: flex;
            flex-wrap: wrap;
            gap: 6px;
            align-items: center;
        }
        .stat-badge {
            display: inline-flex;
            align-items: center;
            gap: 4px;
            padding: 4px 10px;
            border-radius: 14px;
            font-size: 0.68rem;
            font-weight: 600;
            background: var(--accent-light);
            color: var(--accent);
            white-space: nowrap;
        }
        .stat-badge.success {
            background: var(--success-light);
            color: var(--success);
        }
        .stat-badge.warn {
            background: var(--warning-light);
            color: var(--warning);
        }
        .stat-badge.danger {
            background: var(--danger-light);
            color: var(--danger);
        }
        .morse-table {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(75px, 1fr));
            gap: 4px;
            font-family: var(--font-mono);
            font-size: 0.7rem;
        }
        .morse-item {
            background: var(--bg);
            border-radius: var(--radius-sm);
            padding: 5px 7px;
            text-align: center;
            border: 1px solid var(--border);
            transition: all var(--transition);
        }
        .morse-item .char {
            font-weight: 700;
            font-size: 0.82rem;
            color: var(--text);
        }
        .morse-item .code {
            color: var(--accent);
            font-size: 0.62rem;
            letter-spacing: 0.03em;
        }
        .info-tip {
            font-size: 0.7rem;
            color: var(--text-muted);
            padding: 6px 10px;
            background: var(--bg);
            border-radius: var(--radius-sm);
            border: 1px solid var(--border);
            line-height: 1.5;
        }
        .info-tip code {
            background: var(--card-bg);
            padding: 1px 4px;
            border-radius: 3px;
            font-family: var(--font-mono);
            font-size: 0.72rem;
            border: 1px solid var(--border);
        }
        .ad-placeholder {
            border: 1px dashed var(--border);
            border-radius: var(--radius);
            padding: 14px;
            text-align: center;
            color: var(--text-muted);
            font-size: 0.72rem;
            background: var(--bg);
            min-height: 70px;
            display: flex;
            align-items: center;
            justify-content: center;
        }
        .footer {
            background: var(--footer-bg);
            border-top: 1px solid var(--footer-border);
            padding: 24px 20px 20px;
            margin-top: 20px;
            transition: background 0.3s;
        }
        .footer-inner {
            max-width: 1260px;
            margin: 0 auto;
            display: flex;
            flex-wrap: wrap;
            gap: 20px;
            align-items: center;
            justify-content: space-between;
        }
        .footer-copyright {
            font-size: 0.7rem;
            color: var(--text-muted);
        }
        ::-webkit-scrollbar {
            width: 5px;
            height: 5px;
        }
        ::-webkit-scrollbar-track {
            background: transparent;
        }
        ::-webkit-scrollbar-thumb {
            background: #c1c1c6;
            border-radius: 10px;
        }
        [data-theme="dark"] ::-webkit-scrollbar-thumb {
            background: #48484a;
        }
        @media (max-width: 480px) {
            .card {
                padding: 14px 14px;
            }
            textarea {
                font-size: 0.8rem;
                min-height: 80px;
            }
            .output-area {
                font-size: 0.76rem;
                max-height: 180px;
                padding-right: 36px;
            }
            .morse-table {
                grid-template-columns: repeat(auto-fill, minmax(60px, 1fr));
                font-size: 0.62rem;
            }
        }