:root {
            --primary-blue: #00d4ff; --primary-cyan: #00b8d4; --primary-green: #c8ff00; --primary-lime: #76ff03;
            --dark-bg: #0a0a0a; --dark-card: #1a1a1a; --text-primary: #ffffff; --text-secondary: #b0b0b0;
            --gradient-primary: linear-gradient(135deg, var(--primary-blue), var(--primary-cyan), var(--primary-lime), var(--primary-green));
        }
        * { margin: 0; padding: 0; box-sizing: border-box; }
        :focus:not(:focus-visible) { outline: none; }
        * { -webkit-tap-highlight-color: transparent; }
        body { font-family: 'Poppins', sans-serif; background: var(--dark-bg); color: var(--text-primary); overflow-x: hidden; line-height: 1.6; }
        .bg-animation {
            position: fixed; top: 0; left: 0; width: 100%; height: 100%; z-index: 0;
            pointer-events: none;
        }
        .bg-animation::before {
            content: ''; position: absolute; width: 2px; height: 2px; border-radius: 50%;
            background: transparent;
            box-shadow:
                120px 340px #fff, 450px 80px rgba(0,212,255,0.8), 780px 210px #fff,
                230px 560px rgba(200,255,0,0.6), 900px 430px #fff, 60px 700px rgba(0,212,255,0.5),
                1100px 150px #fff, 670px 620px rgba(200,255,0,0.7), 350px 90px #fff,
                820px 380px rgba(0,212,255,0.6), 140px 480px #fff, 990px 260px rgba(200,255,0,0.5),
                500px 750px #fff, 280px 320px rgba(0,212,255,0.7), 1200px 500px #fff,
                75px 190px rgba(200,255,0,0.4), 630px 440px #fff, 1050px 680px rgba(0,212,255,0.6),
                400px 160px #fff, 760px 540px rgba(200,255,0,0.8), 180px 640px #fff,
                920px 90px rgba(0,212,255,0.5), 540px 290px #fff, 310px 720px rgba(200,255,0,0.6),
                1150px 370px #fff, 700px 130px rgba(0,212,255,0.7), 85px 400px #fff,
                1300px 220px #fff, 1400px 600px rgba(0,212,255,0.5), 1250px 750px rgba(200,255,0,0.4),
                30px 850px #fff, 1350px 450px #fff, 600px 900px rgba(0,212,255,0.6);
            animation: starPulse 6s ease-in-out infinite alternate;
        }
        .bg-animation::after {
            content: ''; position: absolute; width: 1px; height: 1px; border-radius: 50%;
            background: transparent;
            box-shadow:
                200px 450px rgba(255,255,255,0.4), 580px 120px rgba(0,212,255,0.3),
                840px 290px rgba(255,255,255,0.5), 110px 600px rgba(200,255,0,0.3),
                1000px 350px rgba(255,255,255,0.4), 440px 670px rgba(0,212,255,0.4),
                720px 200px rgba(255,255,255,0.3), 960px 510px rgba(200,255,0,0.4),
                330px 780px rgba(255,255,255,0.5), 650px 40px rgba(0,212,255,0.3),
                1180px 420px rgba(255,255,255,0.4), 490px 340px rgba(200,255,0,0.5),
                1320px 180px rgba(255,255,255,0.3), 870px 760px rgba(0,212,255,0.4),
                260px 920px rgba(255,255,255,0.4), 1100px 850px rgba(200,255,0,0.3);
            animation: starPulse 9s ease-in-out infinite alternate-reverse;
        }
        @keyframes starPulse { 0%{opacity:0.3} 100%{opacity:1} }
        .shooting-star {
            position: absolute; top: 0; left: 0;
            width: 180px; height: 1px;
            background: linear-gradient(90deg, transparent, rgba(255,255,255,0.9), rgba(0,212,255,0.6), transparent);
            border-radius: 50%;
            filter: drop-shadow(0 0 4px rgba(0,212,255,0.8));
            opacity: 0; transform: rotate(-45deg);
        }
        .shooting-star:nth-child(1) { top: 8%;  left: 20%; animation: shoot 9s  linear 2s   infinite; }
        .shooting-star:nth-child(2) { top: 20%; left: 65%; animation: shoot 11s linear 6s   infinite; width: 220px; }
        .shooting-star:nth-child(3) { top: 5%;  left: 80%; animation: shoot 8s  linear 11s  infinite; width: 140px; }
        .shooting-star:nth-child(4) { top: 40%; left: 10%; animation: shoot 10s linear 16s  infinite; width: 200px; }
        @keyframes shoot {
            0%   { transform: translateX(0) translateY(0) rotate(-45deg); opacity: 0; }
            5%   { opacity: 0.65; }
            60%  { opacity: 0.4; }
            100% { transform: translateX(700px) translateY(700px) rotate(-45deg); opacity: 0; }
        }
        header { position: fixed; top: 0; left: 0; width: 100%; z-index: 1000; background: rgba(10,10,10,0.95); backdrop-filter: blur(10px); border-bottom: 1px solid rgba(0,212,255,0.1); transition: all 0.3s ease; }
        header.scrolled { background: rgba(10,10,10,0.98); box-shadow: 0 10px 30px rgba(0,212,255,0.1); }
        nav { max-width: 1400px; margin: 0 auto; padding: 1rem 2rem; display: flex; justify-content: space-between; align-items: center; }
        .logo-text { font-family: 'Orbitron', sans-serif; font-size: 1.5rem; font-weight: 700; background: var(--gradient-primary); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; letter-spacing: 1px; text-decoration: none; transition: all 0.3s ease; }
        .logo-text:hover { filter: drop-shadow(0 0 10px rgba(0,212,255,0.5)); }
        .nav-links { display: flex; gap: 2rem; list-style: none; }
        .nav-links a { color: var(--text-secondary); text-decoration: none; font-weight: 500; font-size: 0.95rem; transition: all 0.3s ease; position: relative; }
        .nav-links a::after { content: ''; position: absolute; bottom: -5px; left: 0; width: 0; height: 2px; background: var(--gradient-primary); transition: width 0.3s ease; }
        .nav-links a:hover { color: var(--text-primary); }
        .nav-links a:hover::after, .nav-links a.active::after { width: 100%; }
        .nav-links a.active { color: var(--text-primary); }
        .mobile-menu-btn { display: none; background: none; border: none; cursor: pointer; padding: 0.4rem; z-index: 1100; flex-direction: column; justify-content: center; align-items: center; gap: 5px; width: 36px; height: 36px; }
        .mobile-menu-btn span { display: block; width: 22px; height: 2px; background: var(--text-primary); border-radius: 2px; transition: transform 0.3s ease, opacity 0.3s ease, width 0.3s ease; }
        .mobile-menu-btn:hover span { background: var(--primary-cyan); }
        .mobile-menu-btn.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
        .mobile-menu-btn.open span:nth-child(2) { opacity: 0; width: 0; }
        .mobile-menu-btn.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }
        .mobile-menu-btn:hover { border-color: var(--primary-cyan); background: rgba(0,212,255,0.1); }
        .breadcrumb { position: relative; z-index: 10; max-width: 1400px; margin: 0 auto; padding: 7rem 2rem 0; display: flex; align-items: center; gap: 0.5rem; font-size: 0.85rem; color: var(--text-secondary); flex-wrap: wrap; }
        .breadcrumb a { color: var(--text-secondary); text-decoration: none; transition: color 0.3s; }
        .breadcrumb a:hover { color: var(--primary-cyan); }
        .breadcrumb .current { color: var(--text-primary); }
        .page-header { position: relative; z-index: 10; max-width: 1400px; margin: 0 auto; padding: 2rem 2rem 0; }
        .product-tag { display: inline-flex; align-items: center; gap: 0.5rem; background: rgba(0,212,255,0.08); border: 1px solid rgba(0,212,255,0.2); color: var(--primary-cyan); padding: 0.35rem 1rem; border-radius: 50px; font-size: 0.8rem; font-weight: 600; text-transform: uppercase; letter-spacing: 1px; margin-bottom: 1rem; }
        .page-header h1 { font-family: 'Orbitron', sans-serif; font-size: clamp(1.8rem, 4vw, 2.8rem); font-weight: 800; margin-bottom: 0.6rem; background: var(--gradient-primary); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; }
        .page-header p { color: var(--text-secondary); font-size: 1rem; max-width: 600px; }
        .page-header-meta { display: flex; align-items: center; gap: 1.5rem; margin-top: 1.2rem; flex-wrap: wrap; }
        .meta-item { display: flex; align-items: center; gap: 0.4rem; font-size: 0.82rem; color: var(--text-secondary); }
        .divider { position: relative; z-index: 10; max-width: 1400px; margin: 2rem auto 0; padding: 0 2rem; }
        .divider hr { border: none; border-top: 1px solid rgba(255,255,255,0.07); }
        .layout { position: relative; z-index: 10; max-width: 1400px; margin: 0 auto; padding: 2.5rem 2rem 6rem; display: grid; grid-template-columns: 280px 1fr; gap: 3rem; align-items: start; }
        .sidebar { position: sticky; top: 90px; }
        .sidebar-title { font-size: 0.75rem; font-weight: 700; text-transform: uppercase; letter-spacing: 2px; color: var(--text-secondary); margin-bottom: 1rem; padding-bottom: 0.8rem; border-bottom: 1px solid rgba(255,255,255,0.07); }
        .sidebar-search { position: relative; margin-bottom: 1.2rem; }
        .sidebar-search input { width: 100%; padding: 0.6rem 0.8rem 0.6rem 2.2rem; background: var(--dark-card); border: 1px solid rgba(0,212,255,0.15); border-radius: 8px; color: var(--text-primary); font-family: 'Poppins', sans-serif; font-size: 0.82rem; outline: none; transition: all 0.3s ease; }
        .sidebar-search input::placeholder { color: #555; }
        .sidebar-search input:focus { border-color: var(--primary-cyan); }
        .sidebar-search-icon { position: absolute; left: 0.6rem; top: 50%; transform: translateY(-50%); font-size: 0.9rem; pointer-events: none; }
        .article-nav { list-style: none; }
        .article-nav li { margin-bottom: 0.2rem; }
        .article-nav a { display: flex; align-items: center; gap: 0.6rem; padding: 0.6rem 0.8rem; border-radius: 8px; color: var(--text-secondary); text-decoration: none; font-size: 0.85rem; transition: all 0.25s ease; border: 1px solid transparent; }
        .article-nav a:hover { color: var(--text-primary); background: rgba(0,212,255,0.06); border-color: rgba(0,212,255,0.1); }
        .article-nav a.active { color: var(--primary-cyan); background: rgba(0,212,255,0.08); border-color: rgba(0,212,255,0.2); }
        .article-nav .num { width: 20px; height: 20px; border-radius: 50%; background: rgba(0,212,255,0.1); color: var(--primary-cyan); font-size: 0.7rem; font-weight: 700; display: flex; align-items: center; justify-content: center; flex-shrink: 0; }
        .article-nav a.active .num { background: var(--primary-cyan); color: var(--dark-bg); }
        .article-card { background: var(--dark-card); border: 1px solid rgba(0,212,255,0.1); border-radius: 20px; padding: 2.5rem; margin-bottom: 2rem; transition: border-color 0.3s ease, transform 0.3s ease, box-shadow 0.3s ease; position: relative; overflow: hidden; }
        .article-card::before { content: ''; position: absolute; top: 0; left: 0; right: 0; height: 4px; background: var(--gradient-primary); transform: scaleX(0); transition: transform 0.4s ease; }
        .article-card:hover { border-color: rgba(0,212,255,0.3); transform: translateY(-4px); box-shadow: 0 12px 35px rgba(0,212,255,0.12); }
        .article-card:hover::before { transform: scaleX(1); }
        .article-number { display: inline-flex; align-items: center; gap: 0.5rem; font-size: 0.75rem; font-weight: 700; text-transform: uppercase; letter-spacing: 1.5px; color: var(--primary-cyan); margin-bottom: 0.8rem; }
        .article-number::before { content: ''; display: block; width: 20px; height: 2px; background: var(--gradient-primary); border-radius: 2px; }
        .article-card h2 { font-family: 'Orbitron', sans-serif; font-size: clamp(1.1rem, 2.5vw, 1.4rem); font-weight: 700; color: var(--text-primary); margin-bottom: 1.5rem; line-height: 1.4; }
        .article-image-wrap { display:inline-block; width: 100%; border-radius: 12px; overflow: hidden; border: 1px solid rgba(0,212,255,0.15); background: #111; cursor: zoom-in; }
        .article-image-wrap img { width: 100%; height: auto; display: block; transition: transform 0.4s ease; }
        .article-image-wrap:hover img { transform: scale(1.02); }
        .img-natural { display:block; max-width:100%; text-align:center; }
        .img-natural .article-image-wrap { display:inline-block; width:auto; max-width:100%; }
        .img-narrow { display:block; max-width:320px; margin:0 auto; }
        .article-body { color: var(--text-secondary); font-size: 0.95rem; line-height: 1.85; }
        .article-body p { margin-bottom: 1rem; }
        .article-body strong { color: var(--text-primary); font-weight: 600; }
        .step { display: flex; gap: 1rem; align-items: flex-start; background: rgba(0,212,255,0.04); border: 1px solid rgba(0,212,255,0.1); border-radius: 10px; padding: 1rem 1.2rem; margin-bottom: 0.8rem; }
        .step-num { width: 26px; height: 26px; border-radius: 50%; flex-shrink: 0; background: var(--gradient-primary); color: var(--dark-bg); font-weight: 700; font-size: 0.78rem; display: flex; align-items: center; justify-content: center; }
        .step-text { flex: 1; font-size: 0.92rem; padding-top: 0.1rem; }
        .tip { background: rgba(200,255,0,0.05); border-left: 3px solid var(--primary-green); border-radius: 0 8px 8px 0; padding: 0.9rem 1.2rem; margin-top: 1.2rem; font-size: 0.88rem; }
        .tip strong { color: var(--primary-green); }
        .article-nav-bottom { display: flex; justify-content: space-between; gap: 1rem; margin-top: 1rem; flex-wrap: wrap; }
        .nav-btn { display: flex; align-items: center; gap: 0.6rem; padding: 0.8rem 1.4rem; border-radius: 10px; background: var(--dark-card); border: 1px solid rgba(0,212,255,0.15); color: var(--text-secondary); font-size: 0.85rem; transition: all 0.3s ease; flex: 1; min-width: 140px; cursor: pointer; font-family: 'Poppins', sans-serif; text-decoration: none; }
        .nav-btn:hover { border-color: var(--primary-cyan); color: var(--text-primary); background: rgba(0,212,255,0.06); }
        .nav-btn.next { justify-content: flex-end; text-align: right; }
        .help-banner { background: var(--dark-card); border: 1px solid rgba(0,212,255,0.15); border-radius: 16px; padding: 2rem; display: flex; align-items: center; justify-content: space-between; gap: 1.5rem; flex-wrap: wrap; margin-top: 3rem; position: relative; overflow: hidden; }
        .help-banner::before { content: ''; position: absolute; top: -50%; right: -10%; width: 300px; height: 300px; background: radial-gradient(circle, rgba(0,212,255,0.05) 0%, transparent 70%); }
        .help-banner h3 { font-size: 1.1rem; margin-bottom: 0.3rem; position: relative; }
        .help-banner p { color: var(--text-secondary); font-size: 0.88rem; position: relative; }
        .help-banner-actions { display: flex; gap: 0.8rem; flex-wrap: wrap; position: relative; }
        .btn { padding: 0.7rem 1.5rem; font-size: 0.88rem; font-weight: 600; text-decoration: none; border-radius: 50px; transition: all 0.3s ease; cursor: pointer; border: none; font-family: 'Poppins', sans-serif; display: inline-block; }
        .btn-primary { background: var(--gradient-primary); color: var(--dark-bg); }
        .btn-primary:hover { transform: translateY(-2px); box-shadow: 0 8px 25px rgba(0,212,255,0.35); }
        .btn-secondary { background: transparent; color: var(--text-primary); border: 2px solid var(--primary-cyan); }
        .btn-secondary:hover { background: rgba(0,212,255,0.1); transform: translateY(-2px); }
        .lightbox { display: none; position: fixed; inset: 0; background: rgba(0,0,0,0.92); z-index: 9999; align-items: center; justify-content: center; padding: 2rem; }
        .lightbox.open { display: flex; }
        .lightbox img { max-width: 90vw; max-height: 85vh; border-radius: 12px; object-fit: contain; }
        .lightbox-close { position: absolute; top: 1.5rem; right: 1.5rem; background: rgba(255,255,255,0.1); border: none; color: #fff; font-size: 1.5rem; cursor: pointer; width: 44px; height: 44px; border-radius: 50%; display: flex; align-items: center; justify-content: center; transition: background 0.3s; }
        .lightbox-close:hover { background: rgba(255,255,255,0.2); }
        footer { position: relative; z-index: 10; background: var(--dark-card); padding: 1.2rem; text-align: center; border-top: 1px solid rgba(0,212,255,0.1); }
        footer p { color: var(--text-secondary); font-size: 0.9rem; }
        .scroll-top { position: fixed; bottom: 2rem; right: 2rem; width: 46px; height: 46px; background: var(--gradient-primary); border: none; border-radius: 50%; color: var(--dark-bg); font-size: 1.3rem; cursor: pointer; opacity: 0; visibility: hidden; transition: all 0.3s ease; z-index: 1000; display: flex; align-items: center; justify-content: center; }
        .scroll-top.visible { opacity: 1; visibility: visible; }
        .scroll-top:hover { transform: translateY(-4px); box-shadow: 0 8px 25px rgba(0,212,255,0.5); }
        /* =============================================
           FULL RESPONSIVE SYSTEM — ALL DEVICES
           320px phones → 4K TVs
        ============================================= */

        /* === SIDEBAR COLLAPSES AT TABLET === */
        @media (max-width: 1024px) {
            /* Mobile nav overlay */
            .nav-links { position: absolute; top: 100%; left: 0; width: 100%; flex-direction: column; align-items: stretch; gap: 0; list-style: none; background: rgba(10,10,10,0.97); backdrop-filter: blur(20px); border-top: 1px solid rgba(0,212,255,0.12); border-bottom: 1px solid rgba(0,212,255,0.08); padding: 0.4rem 0; opacity: 0; transform: translateY(-6px); pointer-events: none; transition: opacity 0.22s ease, transform 0.22s ease; z-index: 999; }
            .nav-links.active { opacity: 1; transform: translateY(0); pointer-events: auto; }
            .nav-links li { border-bottom: 1px solid rgba(255,255,255,0.04); }
            .nav-links li:last-child { border-bottom: none; }
            .nav-links a { display: block; padding: 0.85rem 1.5rem; font-size: 0.92rem; color: var(--text-secondary); transition: color 0.2s, background 0.2s, padding-left 0.2s; }
            .nav-links a:hover { color: var(--primary-cyan); background: rgba(0,212,255,0.06); padding-left: 2rem; }
            .nav-links a::after { display: none; }
            .mobile-menu-btn { display: flex; align-items: center; justify-content: center; }
            /* Sidebar above content */
            .layout { grid-template-columns: 1fr; gap: 1.5rem; padding: 2rem 2rem 5rem; }
            .sidebar { position: static; margin-bottom: 0; }
            .article-nav { display: flex; flex-wrap: wrap; gap: 0.5rem; }
            .article-nav li { margin-bottom: 0; }
            .article-nav a { font-size: 0.8rem; padding: 0.45rem 0.7rem; white-space: nowrap; }
        }

        /* === TABLETS (769px – 1024px) === */
        @media (min-width: 769px) and (max-width: 1024px) {
            nav { padding: 0.9rem 1.8rem; }
            .breadcrumb { padding: 6.5rem 2rem 0; }
            .page-header { padding: 2rem 2rem 0; }
            .divider { padding: 0 2rem; }
            .layout { padding: 2rem 2rem 5rem; }
            .article-card { padding: 2.2rem 2rem; }
        }

        /* === MOBILE (≤ 768px) === */
        @media (max-width: 768px) {
            .breadcrumb { padding: 6rem 1.5rem 0; flex-wrap: wrap; }
            .page-header, .divider { padding-left: 1.5rem; padding-right: 1.5rem; }
            .page-header h1 { font-size: 1.6rem; }
            .layout { padding: 2rem 1.5rem 5rem; gap: 1.5rem; }
            .article-card { padding: 1.8rem 1.4rem; }
            .step { padding: 0.9rem 1rem; gap: 0.8rem; }
            .step-text { font-size: 0.88rem; }
            .nav-btn { min-width: 120px; font-size: 0.8rem; padding: 0.7rem 1rem; }
            .help-banner { flex-direction: column; padding: 1.8rem; gap: 1.2rem; }
            .help-banner-actions { width: 100%; flex-direction: column; gap: 0.8rem; }
            .btn { width: 100%; text-align: center; }
            .article-body { font-size: 0.9rem; }
        }

        /* === PHONES (≤ 480px) === */
        @media (max-width: 480px) {
            .logo-text { font-size: 1.2rem; }
            nav { padding: 0.8rem 1rem; }
            .breadcrumb { padding: 5.5rem 1rem 0; font-size: 0.78rem; }
            .page-header { padding: 1.5rem 1rem 0; }
            .page-header h1 { font-size: 1.4rem; }
            .page-header p { font-size: 0.88rem; }
            .page-header-meta { gap: 1rem; }
            .divider { padding: 0 1rem; }
            .layout { padding: 1.5rem 1rem 4rem; }
            .article-card { padding: 1.5rem 1rem; border-radius: 14px; }
            .article-card h2 { font-size: 1.1rem; margin-bottom: 1.2rem; }
            .article-nav a { font-size: 0.75rem; padding: 0.4rem 0.6rem; }
            .step { padding: 0.8rem; flex-wrap: nowrap; }
            .step-num { width: 22px; height: 22px; font-size: 0.72rem; }
            .step-text { font-size: 0.85rem; }
            .tip { padding: 0.8rem 1rem; font-size: 0.83rem; }
            .article-body { font-size: 0.88rem; }
            .nav-btn { padding: 0.65rem 0.8rem; font-size: 0.78rem; min-width: 100px; }
            .article-nav-bottom { gap: 0.6rem; }
            .sidebar-title { font-size: 0.7rem; }
            .sidebar-search input { font-size: 0.78rem; }
            .help-banner { padding: 1.5rem 1rem; border-radius: 12px; }
            footer p { font-size: 0.82rem; }
            .scroll-top { width: 44px; height: 44px; font-size: 1.3rem; bottom: 1.2rem; right: 1.2rem; }
        }

        /* === VERY SMALL PHONES (≤ 374px) === */
        @media (max-width: 374px) {
            nav { padding: 0.7rem 0.8rem; }
            .logo-text { font-size: 1rem; letter-spacing: 0; }
            .breadcrumb { padding: 5rem 0.8rem 0; font-size: 0.74rem; }
            .page-header { padding: 1.2rem 0.8rem 0; }
            .page-header h1 { font-size: 1.2rem; }
            .layout { padding: 1.2rem 0.8rem 3rem; }
            .article-card { padding: 1.2rem 0.8rem; }
            .article-card h2 { font-size: 1rem; }
            .article-nav a { font-size: 0.7rem; padding: 0.35rem 0.5rem; }
            .step-text { font-size: 0.82rem; }
            .nav-btn { min-width: 80px; font-size: 0.74rem; padding: 0.55rem 0.6rem; }
            .img-narrow { max-width: 100%; }
            .scroll-top { width: 40px; height: 40px; bottom: 0.8rem; right: 0.8rem; }
        }

        /* Desktop (1025px+) stays exactly as original design — no overrides needed */