/* ===== CSS Variables & Reset ===== */
        :root {
            --bg-primary: #f6f9fc;
            --bg-secondary: #e9f0f5;
            --bg-card: rgba(255, 255, 255, 0.85);
            --bg-card-border: rgba(255,255,255,0.5);
            --text-primary: #0a1e2b;
            --text-secondary: #3a5668;
            --text-muted: #1e3d52;
            --input-bg: #ffffff;
            --input-border: #dbe4ed;
            --input-focus: #2a7faa;
            --btn-primary: #1f6390;
            --btn-primary-hover: #14547c;
            --btn-copy: #eef4fa;
            --btn-copy-hover: #dce8f2;
            --btn-copy-active: #cfe3d9;
            --metric-bg: #e4eef7;
            --metric-border: #cbdde9;
            --toggle-bg: #f2f7fc;
            --toggle-border: #d9e3ed;
            --shadow: 0 25px 45px -12px rgba(0, 20, 30, 0.25);
            --accent: #2a7faa;
            --success: #1f7a5a;
            --transition: 0.3s ease;
            --radius: 2.5rem;
            --font-sans: 'Segoe UI', system-ui, -apple-system, 'Roboto', sans-serif;
            --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
        }

        [data-theme="dark"] {
            --bg-primary: #0d1b26;
            --bg-secondary: #15232e;
            --bg-card: rgba(20, 34, 46, 0.92);
            --bg-card-border: rgba(60, 90, 110, 0.3);
            --text-primary: #e8edf2;
            --text-secondary: #a0bccf;
            --text-muted: #b0c8d8;
            --input-bg: #1a2d3b;
            --input-border: #2d4a5c;
            --input-focus: #4a9bc7;
            --btn-primary: #2a7faa;
            --btn-primary-hover: #3a9bc7;
            --btn-copy: #1e3343;
            --btn-copy-hover: #2a4053;
            --btn-copy-active: #2a5a4a;
            --metric-bg: #1a2d3b;
            --metric-border: #2d4a5c;
            --toggle-bg: #1a2d3b;
            --toggle-border: #2d4a5c;
            --shadow: 0 25px 45px -12px rgba(0, 0, 0, 0.6);
            --accent: #4a9bc7;
            --success: #3a9b7a;
        }

        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: var(--font-sans);
            -webkit-tap-highlight-color: transparent;
        }

        body {
            min-height: 100vh;
            min-height: 100dvh;
            background: linear-gradient(145deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
            display: flex;
            justify-content: center;
            align-items: flex-start;
            padding: 1rem;
            transition: background var(--transition);
        }

        .app-wrapper {
            max-width: 720px;
            width: 100%;
            padding: 0.5rem 0 2rem 0;
        }

        /* ===== Card / Page Container ===== */
        .card, .page-card {
            width: 100%;
            background: var(--bg-card);
            backdrop-filter: blur(8px);
            -webkit-backdrop-filter: blur(8px);
            border-radius: var(--radius);
            padding: 1.8rem 1.5rem;
            box-shadow: var(--shadow);
            border: 1px solid var(--bg-card-border);
            transition: background var(--transition), border var(--transition), box-shadow var(--transition);
            margin-bottom: 1.5rem;
        }

        .page-card {
            padding: 2rem 1.8rem;
        }

        /* ===== Navigation ===== */
        .nav-bar {
            display: flex;
            flex-wrap: wrap;
            gap: 0.4rem 0.6rem;
            margin-bottom: 1.2rem;
            padding: 0.2rem 0.2rem;
            background: var(--toggle-bg);
            border-radius: 3rem;
            border: 1px solid var(--toggle-border);
            transition: background var(--transition), border var(--transition);
        }

        .nav-link {
            padding: 0.4rem 1rem;
            border-radius: 3rem;
            font-size: 0.85rem;
            font-weight: 500;
            color: var(--text-muted);
            text-decoration: none;
            transition: all var(--transition);
            white-space: nowrap;
            background: transparent;
            border: none;
            cursor: pointer;
        }

        .nav-link:hover {
            background: var(--btn-copy-hover);
            color: var(--text-primary);
        }

        .nav-link.active {
            background: var(--btn-primary);
            color: white;
            box-shadow: 0 2px 8px rgba(26, 87, 128, 0.2);
        }

        .nav-link i {
            margin-right: 0.3rem;
            font-size: 0.8rem;
        }

        /* ===== Header ===== */
        .header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 0.5rem;
            gap: 0.6rem;
            flex-wrap: wrap;
        }

        .header-left {
            display: flex;
            align-items: center;
            gap: 0.6rem;
            flex: 1;
            min-width: 0;
        }

        h1 {
            font-size: 1.5rem;
            font-weight: 600;
            color: var(--text-primary);
            display: flex;
            align-items: center;
            gap: 0.4rem;
            transition: color var(--transition);
            white-space: nowrap;
        }

        h1 i { color: var(--accent); font-size: 1.4rem; }

        .theme-toggle {
            background: var(--toggle-bg);
            border: 1px solid var(--toggle-border);
            border-radius: 3rem;
            padding: 0.4rem 0.7rem;
            color: var(--text-primary);
            cursor: pointer;
            font-size: 1rem;
            transition: all var(--transition);
            display: flex;
            align-items: center;
            gap: 0.3rem;
            flex-shrink: 0;
            touch-action: manipulation;
        }

        .theme-toggle:hover {
            background: var(--btn-copy-hover);
            transform: scale(1.02);
        }
        .theme-toggle:active { transform: scale(0.95); }
        .theme-toggle i { font-size: 1rem; }
        .theme-toggle span { font-size: 0.8rem; font-weight: 500; }

        .subhead {
            font-size: 0.85rem;
            color: var(--text-secondary);
            margin-bottom: 1.5rem;
            border-left: 3px solid var(--accent);
            padding-left: 0.8rem;
            background: rgba(42, 127, 170, 0.06);
            border-radius: 0 8px 8px 0;
            transition: color var(--transition), background var(--transition);
            line-height: 1.4;
        }

        /* ===== Password Display ===== */
        .password-display {
            background: var(--input-bg);
            border-radius: 2rem;
            padding: 0.2rem 0.2rem 0.2rem 1.2rem;
            display: flex;
            align-items: center;
            justify-content: space-between;
            box-shadow: inset 0 2px 6px rgba(0,0,0,0.02), 0 6px 14px rgba(0, 20, 30, 0.06);
            border: 1px solid var(--input-border);
            transition: background var(--transition), border var(--transition), box-shadow var(--transition);
            margin-bottom: 1.5rem;
            min-height: 3.8rem;
        }

        .password-display:focus-within {
            border-color: var(--input-focus);
            box-shadow: 0 0 0 3px rgba(42, 127, 170, 0.15);
        }

        #passwordOutput {
            font-size: 1.2rem;
            font-weight: 500;
            letter-spacing: 0.02em;
            color: var(--text-primary);
            background: transparent;
            border: none;
            outline: none;
            width: 100%;
            padding: 0.6rem 0;
            font-family: var(--font-mono);
            word-break: break-all;
            transition: color var(--transition);
            min-width: 0;
        }

        .copy-btn {
            background: var(--btn-copy);
            border: none;
            border-radius: 3rem;
            padding: 0.5rem 1rem;
            margin-right: 0.2rem;
            color: var(--text-muted);
            font-size: 1rem;
            cursor: pointer;
            display: flex;
            align-items: center;
            gap: 0.4rem;
            transition: all 0.15s;
            font-weight: 500;
            white-space: nowrap;
            border: 1px solid transparent;
            touch-action: manipulation;
            flex-shrink: 0;
        }

        .copy-btn:hover {
            background: var(--btn-copy-hover);
            color: var(--text-primary);
            border-color: var(--input-border);
        }
        .copy-btn:active { transform: scale(0.95); }
        .copy-btn.copied {
            background: var(--btn-copy-active);
            color: var(--success);
            border-color: var(--success);
        }
        .copy-btn i { font-size: 0.9rem; }
        .copy-btn span { font-size: 0.85rem; }

        /* ===== Controls ===== */
        .controls {
            display: flex;
            flex-direction: column;
            gap: 1.2rem;
            margin: 1.2rem 0 1.5rem 0;
        }

        .control-row {
            display: flex;
            flex-wrap: wrap;
            align-items: center;
            justify-content: space-between;
            gap: 0.6rem 0.8rem;
        }

        .control-label {
            display: flex;
            align-items: center;
            gap: 0.4rem;
            font-weight: 500;
            color: var(--text-muted);
            font-size: 0.9rem;
            transition: color var(--transition);
        }
        .control-label i {
            width: 1.2rem;
            color: var(--accent);
            font-size: 0.95rem;
        }

        .length-control {
            display: flex;
            align-items: center;
            gap: 0.6rem;
            background: var(--toggle-bg);
            padding: 0.15rem 0.15rem 0.15rem 0.8rem;
            border-radius: 3rem;
            border: 1px solid var(--toggle-border);
            transition: background var(--transition), border var(--transition);
        }

        #lengthSlider {
            width: 120px;
            height: 4px;
            background: var(--input-border);
            border-radius: 10px;
            -webkit-appearance: none;
            appearance: none;
            outline: none;
            transition: background var(--transition);
        }

        #lengthSlider::-webkit-slider-thumb {
            -webkit-appearance: none;
            appearance: none;
            width: 16px;
            height: 16px;
            background: var(--btn-primary);
            border-radius: 50%;
            cursor: pointer;
            box-shadow: 0 2px 6px rgba(0,20,30,0.2);
            border: 2px solid var(--input-bg);
            transition: background var(--transition), border var(--transition);
        }
        #lengthSlider::-webkit-slider-thumb:hover { transform: scale(1.08); }
        #lengthSlider::-moz-range-thumb {
            width: 16px;
            height: 16px;
            background: var(--btn-primary);
            border-radius: 50%;
            cursor: pointer;
            border: 2px solid var(--input-bg);
        }

        #lengthValue {
            min-width: 2.4rem;
            font-weight: 600;
            color: var(--text-primary);
            background: var(--input-bg);
            padding: 0.15rem 0.3rem;
            border-radius: 2rem;
            text-align: center;
            font-size: 0.9rem;
            transition: background var(--transition), color var(--transition);
        }

        .toggle-group {
            display: flex;
            flex-wrap: wrap;
            align-items: center;
            gap: 0.4rem 0.8rem;
        }

        .toggle-item {
            display: flex;
            align-items: center;
            gap: 0.3rem;
            background: var(--toggle-bg);
            padding: 0.2rem 0.7rem 0.2rem 0.5rem;
            border-radius: 3rem;
            border: 1px solid var(--toggle-border);
            font-size: 0.85rem;
            font-weight: 500;
            color: var(--text-muted);
            cursor: pointer;
            transition: all var(--transition);
            touch-action: manipulation;
            user-select: none;
        }
        .toggle-item:hover { background: var(--btn-copy-hover); }
        .toggle-item:active { transform: scale(0.96); }
        .toggle-item input[type="checkbox"] {
            width: 15px;
            height: 15px;
            accent-color: var(--accent);
            cursor: pointer;
            flex-shrink: 0;
        }

        .extra-option {
            display: flex;
            align-items: center;
            gap: 0.4rem;
            background: var(--toggle-bg);
            padding: 0.2rem 0.8rem 0.2rem 0.7rem;
            border-radius: 3rem;
            border: 1px solid var(--toggle-border);
            font-weight: 500;
            color: var(--text-muted);
            transition: all var(--transition);
            font-size: 0.85rem;
            touch-action: manipulation;
            user-select: none;
            cursor: pointer;
        }
        .extra-option:hover { background: var(--btn-copy-hover); }
        .extra-option:active { transform: scale(0.96); }
        .extra-option input[type="checkbox"] {
            width: 15px;
            height: 15px;
            accent-color: var(--accent);
            cursor: pointer;
            flex-shrink: 0;
        }

        .generate-btn {
            background: var(--btn-primary);
            border: none;
            border-radius: 3rem;
            padding: 0.8rem 1.5rem;
            font-weight: 600;
            font-size: 1.05rem;
            color: white;
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 0.6rem;
            cursor: pointer;
            box-shadow: 0 6px 16px rgba(26, 87, 128, 0.25);
            transition: all 0.15s;
            border: 1px solid rgba(255,255,255,0.2);
            width: 100%;
            margin-top: 0.2rem;
            touch-action: manipulation;
        }
        .generate-btn:hover {
            background: var(--btn-primary-hover);
            transform: scale(1.01);
            box-shadow: 0 10px 22px rgba(18, 72, 112, 0.3);
        }
        .generate-btn:active { transform: scale(0.97); }
        .generate-btn i { font-size: 1rem; }
        .generate-btn span { font-size: 1rem; }

        /* ===== Metrics ===== */
        .metrics {
            display: flex;
            flex-wrap: wrap;
            align-items: center;
            justify-content: space-between;
            background: var(--metric-bg);
            border-radius: 3rem;
            padding: 0.7rem 1.2rem;
            margin-top: 1.5rem;
            border: 1px solid var(--metric-border);
            gap: 0.5rem 1rem;
            transition: background var(--transition), border var(--transition);
        }

        .metric-item {
            display: flex;
            align-items: center;
            gap: 0.4rem;
            font-weight: 500;
            color: var(--text-muted);
            font-size: 0.85rem;
            transition: color var(--transition);
        }
        .metric-item i {
            color: var(--accent);
            font-size: 0.95rem;
            width: 1.2rem;
        }
        .metric-value {
            font-weight: 700;
            color: var(--text-primary);
            background: var(--input-bg);
            padding: 0.05rem 0.5rem;
            border-radius: 2rem;
            font-size: 0.8rem;
            border: 1px solid var(--input-border);
            transition: background var(--transition), color var(--transition), border var(--transition);
            white-space: nowrap;
        }
        .metric-value.time {
            background: var(--metric-bg);
            border-color: var(--metric-border);
        }

        /* ===== Footer ===== */
        .footer {
            margin-top: 1.5rem;
            display: flex;
            align-items: center;
            justify-content: space-between;
            flex-wrap: wrap;
            gap: 0.6rem;
            padding-top: 1.2rem;
            border-top: 1px dashed var(--input-border);
            transition: border var(--transition);
        }

        .footer-note {
            font-size: 0.75rem;
            color: var(--text-secondary);
            transition: color var(--transition);
            display: flex;
            align-items: center;
            gap: 0.4rem;
        }
        .footer-note i { color: var(--success); font-size: 0.8rem; }

        .lang-toggle {
            background: var(--toggle-bg);
            border: 1px solid var(--toggle-border);
            border-radius: 3rem;
            padding: 0.3rem 0.6rem;
            color: var(--text-primary);
            cursor: pointer;
            font-size: 1.1rem;
            transition: all var(--transition);
            display: flex;
            align-items: center;
            justify-content: center;
            touch-action: manipulation;
            flex-shrink: 0;
            min-width: 2.4rem;
            min-height: 2.4rem;
        }
        .lang-toggle:hover {
            background: var(--btn-copy-hover);
            transform: scale(1.05);
        }
        .lang-toggle:active { transform: scale(0.92); }
        .lang-toggle i { font-size: 1.2rem; }

        /* ===== Copyright ===== */
        .copyright {
            text-align: center;
            font-size: 0.7rem;
            color: var(--text-secondary);
            padding: 0.8rem 0 0.2rem 0;
            opacity: 0.7;
            transition: color var(--transition), opacity var(--transition);
            letter-spacing: 0.3px;
        }
        .copyright i {
            font-size: 0.6rem;
            margin: 0 0.2rem;
        }

        /* ===== Page Content (FAQ / Privacy / Security) ===== */
        .page-title {
            font-size: 1.6rem;
            font-weight: 600;
            color: var(--text-primary);
            margin-bottom: 0.3rem;
            display: flex;
            align-items: center;
            gap: 0.6rem;
        }
        .page-title i { color: var(--accent); }

        .page-meta {
            font-size: 0.85rem;
            color: var(--text-secondary);
            margin-bottom: 1.5rem;
            border-left: 3px solid var(--accent);
            padding-left: 0.8rem;
        }

        .page-content h2 {
            font-size: 1.2rem;
            font-weight: 600;
            color: var(--text-primary);
            margin: 1.4rem 0 0.5rem 0;
        }
        .page-content h2:first-of-type { margin-top: 0; }

        .page-content h3 {
            font-size: 1rem;
            font-weight: 600;
            color: var(--text-primary);
            margin: 1.2rem 0 0.3rem 0;
        }

        .page-content p {
            font-size: 0.92rem;
            line-height: 1.6;
            color: var(--text-secondary);
            margin-bottom: 0.8rem;
        }

        .page-content ul, .page-content ol {
            padding-left: 1.5rem;
            margin-bottom: 0.8rem;
        }
        .page-content li {
            font-size: 0.9rem;
            line-height: 1.6;
            color: var(--text-secondary);
            margin-bottom: 0.3rem;
        }

        .page-content .highlight-box {
            background: var(--metric-bg);
            border-left: 4px solid var(--accent);
            padding: 0.8rem 1.2rem;
            border-radius: 0.8rem;
            margin: 1rem 0;
            transition: background var(--transition);
        }
        .page-content .highlight-box p { margin-bottom: 0; }

        .page-content .icon-list {
            list-style: none;
            padding-left: 0;
        }
        .page-content .icon-list li {
            display: flex;
            gap: 0.6rem;
            align-items: flex-start;
            padding: 0.3rem 0;
        }
        .page-content .icon-list li i {
            color: var(--accent);
            font-size: 0.9rem;
            margin-top: 0.2rem;
            width: 1.2rem;
        }

        /* ===== Responsive ===== */
        @media (max-width: 480px) {
            .card, .page-card { padding: 1.2rem 1rem; border-radius: 1.8rem; }
            .page-card { padding: 1.5rem 1rem; }
            h1 { font-size: 1.2rem; }
            h1 i { font-size: 1.1rem; }
            #passwordOutput { font-size: 1rem; }
            .password-display { padding: 0.15rem 0.15rem 0.15rem 0.8rem; min-height: 3.2rem; }
            .copy-btn { padding: 0.4rem 0.7rem; font-size: 0.85rem; }
            .copy-btn i { font-size: 0.8rem; }
            .copy-btn span { font-size: 0.75rem; }
            .control-label { font-size: 0.8rem; }
            .control-label i { font-size: 0.85rem; width: 1rem; }
            #lengthSlider { width: 80px; }
            #lengthValue { font-size: 0.8rem; min-width: 2rem; }
            .toggle-item { font-size: 0.75rem; padding: 0.15rem 0.5rem 0.15rem 0.4rem; }
            .toggle-item input[type="checkbox"] { width: 13px; height: 13px; }
            .extra-option { font-size: 0.75rem; padding: 0.15rem 0.6rem 0.15rem 0.5rem; }
            .extra-option input[type="checkbox"] { width: 13px; height: 13px; }
            .generate-btn { padding: 0.7rem 1rem; font-size: 0.9rem; }
            .generate-btn i { font-size: 0.85rem; }
            .generate-btn span { font-size: 0.9rem; }
            .metrics { padding: 0.5rem 0.8rem; border-radius: 2rem; gap: 0.4rem 0.6rem; }
            .metric-item { font-size: 0.75rem; gap: 0.3rem; }
            .metric-item i { font-size: 0.8rem; width: 1rem; }
            .metric-value { font-size: 0.7rem; padding: 0.05rem 0.35rem; }
            .subhead { font-size: 0.75rem; padding-left: 0.6rem; margin-bottom: 1rem; }
            .theme-toggle { padding: 0.3rem 0.5rem; font-size: 0.85rem; }
            .theme-toggle i { font-size: 0.85rem; }
            .theme-toggle span { font-size: 0.7rem; }
            .footer { padding-top: 0.8rem; margin-top: 1rem; }
            .footer-note { font-size: 0.65rem; }
            .lang-toggle { font-size: 0.95rem; min-width: 2rem; min-height: 2rem; padding: 0.2rem 0.5rem; }
            .lang-toggle i { font-size: 1rem; }
            .page-title { font-size: 1.3rem; }
            .page-content h2 { font-size: 1.05rem; }
            .page-content h3 { font-size: 0.95rem; }
            .page-content p, .page-content li { font-size: 0.85rem; }
            .nav-link { font-size: 0.75rem; padding: 0.3rem 0.7rem; }
            .nav-link i { font-size: 0.7rem; }
            .nav-bar { gap: 0.2rem 0.4rem; padding: 0.15rem; border-radius: 2rem; flex-wrap: nowrap; overflow-x: scroll; }
            .copyright { font-size: 0.6rem; }
        }

        @media (max-width: 380px) {
            .card { padding: 0.8rem 0.7rem; }
            #lengthSlider { width: 60px; }
            .header { gap: 0.4rem; }
            h1 { font-size: 1rem; }
            .theme-toggle span { display: none; }
        }

        @media (min-width: 600px) {
            #lengthSlider { width: 160px; }
            h1 { font-size: 1.8rem; }
            #passwordOutput { font-size: 1.4rem; }
        }

        /* ===== Utility ===== */
        .hidden { display: none !important; }
        .mt-1 { margin-top: 1rem; }
        .mb-1 { margin-bottom: 1rem; }
        .text-center { text-align: center; }