        :root {
            --bg: #0a0a0a;
            --surface: #151515;
            --primary: #ffffff;
            --accent: #f6f8f7;
            --error: #ff4d4d;
            --success: #e8ebea;
            --grid: rgba(255,255,255,0.03);
            --glow: rgba(99, 99, 99, 0.1);
        }

        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Inter', sans-serif;
            -webkit-font-smoothing: antialiased;
        }

        body {
            background: var(--bg);
            color: var(--primary);
            min-height: 100vh;
            display: grid;
            place-items: center;
            padding: 2rem;
            position: relative;
            overflow: hidden;
        }

        .grid-bg {
            position: fixed;
            width: 100vw;
            height: 100vh;
            background-image: 
                linear-gradient(var(--grid) 1px, transparent 1px),
                linear-gradient(90deg, var(--grid) 1px, transparent 1px);
            background-size: 24px 24px;
            z-index: 0;
        }

        .ambient-glow {
            position: fixed;
            width: 150vw;
            height: 150vh;
            background: radial-gradient(circle at 50% 50%, 
                var(--glow) 0%, 
                transparent 60%);
            filter: blur(100px);
            z-index: 0;
            animation: glowPulse 8s infinite alternate;
        }

        .container {
            background: var(--surface);
            width: 100%;
            max-width: 520px;
            padding: 3rem;
            border-radius: 16px;
            border: 1px solid rgba(255,255,255,0.08);
            box-shadow: 0 0 40px var(--glow);
            position: relative;
            z-index: 1;
        }

        .logo {
            text-align: center;
            font-size: 2.25rem;
            font-weight: 700;
            margin-bottom: 3rem;
            position: relative;
            background: linear-gradient(45deg, #ffffff, #e0e0e0);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            text-shadow: 0 0 15px rgba(255,255,255,0.1);
        }

        .input-container {
            margin-bottom: 1.5rem;
            position: relative;
        }

        .key-input {
            width: 100%;
            padding: 1.25rem;
            background: rgba(255,255,255,0.03);
            border: 1px solid rgba(255,255,255,0.1);
            border-radius: 10px;
            color: var(--primary);
            font-size: 1rem;
            transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
        }

        .key-input:focus {
            outline: none;
            border-color: rgba(255,255,255,0.3);
            box-shadow: 0 0 20px var(--glow);
        }

        .validation-message {
            height: 24px;
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 0.75rem;
            margin: 1.5rem 0;
            font-size: 0.95rem;
            opacity: 0;
            transform: translateY(5px);
            transition: all 0.3s ease;
        }

        .validation-message.visible {
            opacity: 1;
            transform: translateY(0);
        }

        .validation-icon {
            width: 20px;
            height: 20px;
        }

        .download-btn {
            width: 100%;
            padding: 1.25rem;
            background: var(--primary);
            color: var(--bg);
            border: none;
            border-radius: 10px;
            font-weight: 600;
            cursor: pointer;
            display: none;
            align-items: center;
            justify-content: center;
            gap: 0.75rem;
            transition: all 0.3s ease;
            position: relative;
            overflow: hidden;
        }

        .download-btn::before {
            content: '';
            position: absolute;
            top: 0;
            left: -100%;
            width: 100%;
            height: 100%;
            background: linear-gradient(
                90deg,
                transparent,
                rgba(255,255,255,0.1),
                transparent
            );
            transition: 0.5s;
        }

        .download-btn:hover::before {
            left: 100%;
        }

        .security-footer {
            text-align: center;
            margin-top: 2.5rem;
            font-size: 0.9rem;
            color: rgba(255,255,255,0.4);
        }

        @keyframes glowPulse {
            0% { opacity: 0.3; }
            50% { opacity: 0.6; }
            100% { opacity: 0.3; }
        }

        @media (max-width: 480px) {
            .container {
                padding: 2rem;
            }
            
            .logo {
                font-size: 1.75rem;
            }
        }