:root {
            --neon-pink: #ff2a6d;
            --neon-blue: #01c8ee;
            --neon-purple: #ae5ff8;
            --neon-green: #05ffa1;
            --space-blue: #0b3d91;
            --cosmic-purple: #6633cc;
            --dark-bg: #05060f;
            --darker-bg: #02030a;
            --accent-color: #ff2a6d;
            --star-color: #ffffff;
            --nebula-color1: rgba(174, 95, 248, 0.2);
            --nebula-color2: rgba(1, 200, 238, 0.2);
            --nebula-color3: rgba(255, 42, 109, 0.2);
        }
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Courier New', monospace;
        }
        body {
            background-color: var(--dark-bg);
            color: #ffffff;
            overflow-x: hidden;
            min-height: 100vh;
            display: flex;
            flex-direction: column;
            margin: 0;
            padding: 0;
        }
        body::-webkit-scrollbar {
            display: none;
        }
        /* Nền bầu trời đầy sao */
        .stars-container {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            overflow: hidden;
            z-index: -2;
        }
        .star {
            position: absolute;
            width: 2px;
            height: 2px;
            background-color: var(--star-color);
            border-radius: 50%;
            opacity: 0;
            animation: twinkle var(--duration) infinite ease-in-out var(--delay);
        }
        @keyframes twinkle {
            0%, 100% { opacity: 0; transform: scale(0.5); }
            50% { opacity: var(--opacity); transform: scale(1); }
        }
        /* Hiệu ứng sao băng */
        .shooting-star {
            position: absolute;
            width: 150px;
            height: 1px;
            background: linear-gradient(90deg, rgba(255,255,255,0), rgba(255,255,255,1));
            opacity: 0;
            transform-origin: right;
            animation: shooting var(--duration) infinite linear var(--delay);
        }
        @keyframes shooting {
            0% { opacity: 0; transform: translateX(0) }
            5% { opacity: 1; }
            20% { opacity: 1; }
            30% { opacity: 0; transform: translateX(-200px) }
            100% { opacity: 0; transform: translateX(-200px) }
        }
        /* Hiệu ứng tinh vân */
        .nebula {
            position: fixed;
            border-radius: 50%;
            filter: blur(60px);
            opacity: 0.4;
            z-index: -1;
            animation: nebula-float 30s infinite alternate ease-in-out;
        }
        @keyframes nebula-float {
            0% { transform: translate(0, 0) rotate(0deg); }
            100% { transform: translate(50px, 50px) rotate(10deg); }
        }
        /* Quỹ đạo hành tinh */
        .orbit {
            position: fixed;
            border-radius: 50%;
            border: 1px solid rgba(255, 255, 255, 0.1);
            z-index: -1;
            animation: orbit-rotate 60s linear infinite;
        }
        .planet {
            position: absolute;
            border-radius: 50%;
            transform-origin: center;
            animation: planet-glow 4s ease-in-out infinite alternate;
        }
        @keyframes orbit-rotate {
            0% { transform: rotate(0deg); }
            100% { transform: rotate(360deg); }
        }
        @keyframes planet-glow {
            0% { box-shadow: 0 0 10px 2px var(--glow-color); }
            100% { box-shadow: 0 0 20px 5px var(--glow-color); }
        }
        .noise {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 200 200' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noiseFilter'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.65' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noiseFilter)' opacity='0.05'/%3E%3C/svg%3E");
            pointer-events: none;
            opacity: 0.15;
            z-index: 1;
        }
        .container {
            max-width: 1200px;
            width: 100%;
            margin: 0 auto;
            padding: 2rem;
            position: relative;
            z-index: 2;
            flex: 1;
            display: flex;
            flex-direction: column;
        }
        header {
            text-align: center;
            margin-bottom: 4rem;
            position: relative;
        }
        h1 {
            font-size: 3.5rem;
            font-weight: 700;
            letter-spacing: 2px;
            margin-bottom: 1rem;
            text-transform: uppercase;
            background: linear-gradient(90deg, var(--neon-blue), var(--neon-pink), var(--neon-purple));
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            position: relative;
            display: inline-block;
        }
        h1::after {
            content: "Miễn phí AI";
            position: absolute;
            left: 0;
            top: 0;
            width: 100%;
            height: 100%;
            background: none;
            -webkit-text-fill-color: transparent;
            text-shadow:
                0 0 5px var(--neon-blue),
                0 0 10px var(--neon-pink),
                0 0 15px var(--neon-purple),
                0 0 20px var(--neon-green);
            animation: flicker 4s infinite alternate;
            opacity: 0.7;
        }
        @keyframes flicker {
            0%, 19.999%, 22%, 62.999%, 64%, 64.999%, 70%, 100% {
                opacity: 0.9;
                text-shadow:
                    0 0 5px var(--neon-blue),
                    0 0 10px var(--neon-pink),
                    0 0 15px var(--neon-purple),
                    0 0 20px var(--neon-green);
            }
            20%, 21.999%, 63%, 63.999%, 65%, 69.999% {
                opacity: 0.4;
                text-shadow: none;
            }
        }
        .subtitle {
            font-size: 1.2rem;
            margin-bottom: 2rem;
            color: rgba(255, 255, 255, 0.7);
            text-transform: uppercase;
            letter-spacing: 3px;
            position: relative;
        }
        .subtitle::after {
            content: '';
            position: absolute;
            bottom: -15px;
            left: 50%;
            transform: translateX(-50%);
            width: 150px;
            height: 1px;
            background: linear-gradient(90deg, transparent, var(--neon-purple), transparent);
        }
        .grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 2rem;
        }
        .card {
            background: rgba(5, 6, 15, 0.8);
            border-radius: 10px;
            padding: 2rem;
            transition: all 0.5s cubic-bezier(0.175, 0.885, 0.32, 1.275);
            position: relative;
            overflow: hidden;
            border: 1px solid rgba(255, 255, 255, 0.1);
            box-shadow: 0 0 15px rgba(1, 200, 238, 0.15);
            backdrop-filter: blur(10px);
            transform-style: preserve-3d;
        }
        .card::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 5px;
            background: linear-gradient(90deg, var(--neon-blue), var(--neon-pink), var(--neon-purple));
            z-index: 1;
        }
        .card::after {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: radial-gradient(circle at 50% 50%, rgba(1, 200, 238, 0.1), transparent 70%);
            opacity: 0;
            transition: opacity 0.5s ease;
            z-index: 0;
        }
        .card:hover {
            transform: translateY(-15px) rotateX(5deg) rotateY(5deg);
            box-shadow:
                0 0 20px rgba(1, 200, 238, 0.3),
                0 0 40px rgba(174, 95, 248, 0.2);
        }
        .card:hover::after {
            opacity: 1;
        }
        .card:nth-child(1)::before {
            background: linear-gradient(90deg, var(--neon-blue), var(--neon-pink));
        }
        .card:nth-child(2)::before {
            background: linear-gradient(90deg, var(--neon-pink), var(--neon-purple));
        }
        .card:nth-child(3)::before {
            background: linear-gradient(90deg, var(--neon-purple), var(--neon-green));
        }
        .card-content {
            position: relative;
            z-index: 2;
        }
        .star-dust {
            position: absolute;
            width: 100%;
            height: 100%;
            top: 0;
            left: 0;
            pointer-events: none;
            z-index: 1;
            overflow: hidden;
            opacity: 0;
            transition: opacity 0.3s ease;
        }
        .card:hover .star-dust {
            opacity: 1;
        }
        .dust-particle {
            position: absolute;
            width: 2px;
            height: 2px;
            background: white;
            border-radius: 50%;
            animation: float-up 3s linear infinite;
        }
        @keyframes float-up {
            0% { transform: translateY(100%) scale(0); opacity: 0; }
            20% { opacity: 1; }
            80% { opacity: 1; }
            100% { transform: translateY(-100px) scale(1); opacity: 0; }
        }
        .card-icon {
            font-size: 3rem;
            margin-bottom: 1.5rem;
            display: inline-block;
            position: relative;
        }
        .card-icon::after {
            content: '';
            position: absolute;
            width: 50px;
            height: 50px;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
            background: radial-gradient(circle, rgba(255,255,255,0.2) 0%, transparent 70%);
            border-radius: 50%;
            z-index: -1;
        }
        .card:nth-child(1) .card-icon {
            color: var(--neon-blue);
            text-shadow: 0 0 10px var(--neon-blue);
        }
        .card:nth-child(2) .card-icon {
            color: var(--neon-pink);
            text-shadow: 0 0 10px var(--neon-pink);
        }
        .card:nth-child(3) .card-icon {
            color: var(--neon-purple);
            text-shadow: 0 0 10px var(--neon-purple);
        }
        /* New card icon colors */
        .card-icon.stt-icon {
            color: var(--neon-green);
            text-shadow: 0 0 10px var(--neon-green);
        }
        .card-icon.dalle-icon {
            color: #FF6600;
            text-shadow: 0 0 10px #FF6600;
        }
        .card-icon.imagen-icon {
            color: #8A2BE2;
            text-shadow: 0 0 10px #8A2BE2;
        }
        .card-icon.arta-icon {
            color: #00FFFF;
            text-shadow: 0 0 10px #00FFFF;
        }
        .card-icon.donate-icon { /* New icon style for donate card */
            color: #FD7B68; /* A warm, inviting color */
            text-shadow: 0 0 10px #FD7B68;
        }

        .card h2 {
            font-size: 1.8rem;
            margin-bottom: 1rem;
            color: #ffffff;
            text-shadow: 0 0 5px rgba(255, 255, 255, 0.5);
        }
        .card p {
            color: rgba(255, 255, 255, 0.7);
            margin-bottom: 2rem;
            font-size: 1rem;
            line-height: 1.6;
        }
        .btn {
            display: inline-block;
            background: rgba(0, 0, 0, 0.3);
            border: 2px solid var(--accent-color);
            color: var(--accent-color);
            padding: 0.75rem 1.5rem;
            border-radius: 5px;
            text-transform: uppercase;
            font-weight: bold;
            letter-spacing: 2px;
            font-size: 0.8rem;
            transition: all 0.3s ease;
            position: relative;
            overflow: hidden;
            z-index: 1;
            text-decoration: none;
        }
        .btn::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            width: 0%;
            height: 100%;
            background: var(--accent-color);
            transition: all 0.3s ease;
            z-index: -1;
        }
        .btn:hover {
            color: #000;
            box-shadow: 0 0 15px var(--accent-color);
        }
        .btn:hover::before {
            width: 100%;
        }
        .card:nth-child(1) .btn {
            border-color: var(--neon-blue);
            color: var(--neon-blue);
        }
        .card:nth-child(1) .btn::before {
            background: var(--neon-blue);
        }
        .card:nth-child(2) .btn {
            border-color: var(--neon-pink);
            color: var(--neon-pink);
        }
        .card:nth-child(2) .btn::before {
            background: var(--neon-pink);
        }
        .card:nth-child(3) .btn {
            border-color: var(--neon-purple);
            color: var(--neon-purple);
        }
        .card:nth-child(3) .btn::before {
            background: var(--neon-purple);
        }
        /* New button colors for new cards */
        .card .btn.stt-btn {
            border-color: var(--neon-green);
            color: var(--neon-green);
        }
        .card .btn.stt-btn::before {
            background: var(--neon-green);
        }
        .card .btn.dalle-btn {
            border-color: #FF6600;
            color: #FF6600;
        }
        .card .btn.dalle-btn::before {
            background: #FF6600;
        }
        .card .btn.imagen-btn {
            border-color: #8A2BE2;
            color: #8A2BE2;
        }
        .card .btn.imagen-btn::before {
            background: #8A2BE2;
        }
        .card .btn.arta-btn {
            border-color: #00FFFF;
            color: #00FFFF;
        }
        .card .btn.arta-btn::before {
            background: #00FFFF;
        }
        .card .btn.donate-btn { /* New button style for donate card */
            border-color: #FD7B68;
            color: #FD7B68;
        }
        .card .btn.donate-btn::before {
            background: #FD7B68;
        }

        .code-lines {
            position: absolute;
            left: 0;
            top: 0;
            width: 100%;
            height: 100%;
            pointer-events: none;
            opacity: 0.1;
            z-index: 0;
            background-size: 20px 20px;
            background-image: linear-gradient(to right, rgba(255, 255, 255, 0.1) 1px, transparent 1px),
                              linear-gradient(to bottom, rgba(255, 255, 255, 0.1) 1px, transparent 1px);
        }
        .circuit-lines {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            pointer-events: none;
            z-index: 0;
            overflow: hidden;
        }
        .circuit-line {
            position: absolute;
            background: rgba(1, 200, 238, 0.1);
            overflow: hidden;
        }
        .circuit-line::before {
            content: '';
            position: absolute;
            top: 0;
            left: -100%;
            width: 100%;
            height: 100%;
            background: linear-gradient(90deg, transparent, rgba(1, 200, 238, 0.5), transparent);
            animation: circuitPulse 3s infinite linear;
        }
        @keyframes circuitPulse {
            0% { left: -100%; }
            100% { left: 200%; }
        }
        .circuit-line:nth-child(1) {
            width: 3px;
            height: 40%;
            top: 0;
            left: 10%;
        }
        .circuit-line:nth-child(2) {
            width: 2px;
            height: 30%;
            top: 50%;
            left: 20%;
        }
        .circuit-line:nth-child(3) {
            width: 60%;
            height: 2px;
            top: 30%;
            left: 30%;
        }
        .circuit-line:nth-child(4) {
            width: 3px;
            height: 35%;
            top: 40%;
            left: 80%;
        }
        .circuit-line:nth-child(5) {
            width: 40%;
            height: 3px;
            top: 85%;
            left: 10%;
        }
        .circuit-line:nth-child(6) {
            width: 2px;
            height: 20%;
            top: 10%;
            left: 60%;
        }
        .circuit-line:nth-child(7) {
            width: 50%;
            height: 2px;
            top: 60%;
            left: 40%;
        }
        .glitch {
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            overflow: hidden;
            opacity: 0.1;
            pointer-events: none;
            z-index: 1;
        }
        .glitch span {
            position: absolute;
            background: rgba(255, 42, 109, 0.5);
            width: 100%;
            height: 5px;
            animation: glitchEffect 4s infinite;
            opacity: 0;
        }
        .glitch span:nth-child(1) {
            top: 30%;
            animation-delay: 0s;
        }
        .glitch span:nth-child(2) {
            top: 50%;
            animation-delay: 1s;
        }
        .glitch span:nth-child(3) {
            top: 70%;
            animation-delay: 2s;
        }
        @keyframes glitchEffect {
            0% {
                opacity: 0;
                transform: translateX(-100%);
            }
            0.5%, 1.5% {
                opacity: 0.5;
                transform: translateX(0);
            }
            2% {
                opacity: 0;
                transform: translateX(100%);
            }
            100% {
                opacity: 0;
                transform: translateX(100%);
            }
        }
        .digital-clock {
            position: absolute;
            top: 20px;
            right: 20px;
            font-family: 'Courier New', monospace;
            font-size: 1rem;
            color: var(--neon-green);
            background: rgba(0, 0, 0, 0.5);
            padding: 0.5rem 1rem;
            border-radius: 5px;
            border: 1px solid rgba(5, 255, 161, 0.3);
            text-shadow: 0 0 5px var(--neon-green);
            letter-spacing: 2px;
            backdrop-filter: blur(5px);
        }
        footer {
            margin-top: 6rem;
            text-align: center;
            color: rgba(255, 255, 255, 0.5);
            font-size: 0.8rem;
            letter-spacing: 1.5px;
            position: relative;
            z-index: 5;
            padding: 2rem 0;
            width: 100%;
        }
        footer::before {
            content: '';
            position: absolute;
            top: 0;
            left: 50%;
            transform: translateX(-50%);
            width: 200px;
            height: 1px;
            background: linear-gradient(90deg, transparent, rgba(255,255,255,0.3), transparent);
        }
        footer a {
            position: relative;
            transition: all 0.3s ease;
        }
        footer a:hover {
            color: var(--neon-blue);
            text-shadow: 0 0 5px var(--neon-blue);
        }
        @media (max-width: 768px) {
            h1 {
                font-size: 2.5rem;
            }
            .subtitle {
                font-size: 1rem;
            }
            .grid {
                grid-template-columns: 1fr;
            }
            .card {
                padding: 1.5rem;
            }
            .nebula, .orbit {
                display: none;
            }
        }
        @media (max-width: 480px) {
            h1 {
                font-size: 2rem;
            }
            .container {
                padding: 1rem;
            }
            .digital-clock {
                position: relative;
                top: auto;
                right: auto;
                margin: 1rem auto;
                display: inline-block;
            }
        }