/* --- THIẾT LẬP MÀU SẮC & CƠ BẢN --- */
        :root {
            /* Tông màu trầm (Slate Theme) - Refined */
            --bg-body: #0f172a;       /* Darker Slate */
            --bg-card: #1e293b;       /* Slate 800 */
            --bg-card-hover: #334155; /* Slate 700 */
            --text-main: #e2e8f0;     /* Slate 200 */
            --text-muted: #94a3b8;    /* Slate 400 */
            --accent: #38bdf8;        /* Sky 400 */
            --accent-glow: rgba(56, 189, 248, 0.3);
            --secondary: #64748b;     /* Slate 500 */
            
            --padding-section: 100px 20px;
            --max-width: 1100px;
            --nav-height: 80px;
        }

        * { margin: 0; padding: 0; box-sizing: border-box; }
        
        body {
            font-family: 'Inter', sans-serif;
            background-color: var(--bg-body);
            color: var(--text-main);
            line-height: 1.7;
            overflow-x: hidden;
        }

        /* Canvas Background */
        #bg-canvas {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            z-index: -1;
            opacity: 0.4;
        }

        a { text-decoration: none; color: inherit; transition: 0.3s; }
        ul { list-style: none; }

        /* Scrollbar */
        ::-webkit-scrollbar { width: 10px; }
        ::-webkit-scrollbar-track { background: var(--bg-body); }
        ::-webkit-scrollbar-thumb { background: var(--bg-card); border-radius: 5px; }
        ::-webkit-scrollbar-thumb:hover { background: var(--secondary); }

        /* --- HEADER & NAV --- */
        header {
            position: fixed;
            top: 0;
            width: 100%;
            height: var(--nav-height);
            background: rgba(15, 23, 42, 0.85);
            backdrop-filter: blur(12px);
            z-index: 1000;
            border-bottom: 1px solid rgba(255,255,255,0.05);
            transition: transform 0.3s ease-in-out;
        }

        nav {
            max-width: var(--max-width);
            height: 100%;
            margin: 0 auto;
            display: flex;
            justify-content: space-between;
            align-items: center;
            padding: 0 20px;
        }

        .logo { 
            font-size: 1.5rem; 
            font-weight: 700; 
            color: var(--accent); 
            font-family: 'Fira Code', monospace;
            letter-spacing: -1px;
        }
        
        .nav-links { display: flex; gap: 40px; }
        .nav-links a { 
            font-size: 0.9rem; 
            font-weight: 500; 
            color: var(--text-main); 
            position: relative;
            font-family: 'Fira Code', monospace;
        }
        
        .nav-links a::before {
            content: '';
            position: absolute;
            bottom: -5px;
            left: 0;
            width: 0;
            height: 2px;
            background-color: var(--accent);
            transition: width 0.3s ease;
        }

        .nav-links a:hover { color: var(--accent); }
        .nav-links a:hover::before { width: 100%; }

        /* --- GENERAL SECTION STYLES --- */
        section {
            padding: var(--padding-section);
            max-width: var(--max-width);
            margin: 0 auto;
        }

        .section-header {
            display: flex;
            align-items: center;
            margin-bottom: 50px;
            width: 100%;
        }

        .section-header h2 {
            font-size: 2rem;
            color: var(--text-main);
            margin-right: 20px;
            white-space: nowrap;
        }
        
        .section-header h2 span { color: var(--accent); font-family: 'Fira Code', monospace; font-size: 1.5rem; margin-right: 10px; }

        .section-header::after {
            content: '';
            display: block;
            width: 300px;
            height: 1px;
            background-color: var(--bg-card-hover);
        }

        /* --- HERO SECTION --- */
        .hero {
            min-height: 100vh;
            display: flex;
            flex-direction: column;
            justify-content: center;
            align-items: flex-start;
            padding-top: 0;
        }

        .hero-intro {
            color: var(--accent);
            font-family: 'Fira Code', monospace;
            margin-bottom: 20px;
            font-size: 1.1rem;
        }

        .hero h1 {
            font-size: 4.5rem;
            line-height: 1.1;
            margin-bottom: 10px;
            font-weight: 700;
            color: var(--text-main);
        }

        .hero h2 {
            font-size: 3.5rem;
            line-height: 1.1;
            margin-bottom: 30px;
            color: var(--text-muted);
            font-weight: 700;
        }

        .hero p {
            max-width: 540px;
            font-size: 1.1rem;
            color: var(--text-muted);
            margin-bottom: 50px;
        }

        .btn {
            display: inline-block;
            padding: 16px 32px;
            background-color: transparent;
            border: 1px solid var(--accent);
            color: var(--accent);
            border-radius: 4px;
            font-family: 'Fira Code', monospace;
            font-size: 0.9rem;
            cursor: pointer;
            position: relative;
            overflow: hidden;
            z-index: 1;
        }

        .btn::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            width: 0;
            height: 100%;
            background-color: rgba(56, 189, 248, 0.1);
            z-index: -1;
            transition: width 0.3s ease;
        }

        .btn:hover::before { width: 100%; }
        .btn:hover { transform: translateY(-3px); box-shadow: 0 5px 15px rgba(56, 189, 248, 0.2); }

        /* --- ABOUT SECTION --- */
        .about-content {
            display: grid;
            grid-template-columns: 3fr 2fr;
            gap: 50px;
        }

        .about-text p { margin-bottom: 15px; color: var(--text-muted); }
        
        .skills-list {
            display: grid;
            grid-template-columns: repeat(2, 1fr);
            gap: 10px;
            margin-top: 20px;
        }

        .skills-list li {
            position: relative;
            padding-left: 20px;
            font-family: 'Fira Code', monospace;
            font-size: 0.9rem;
            color: var(--text-muted);
        }

        .skills-list li::before {
            content: '▹';
            position: absolute;
            left: 0;
            color: var(--accent);
        }

        .about-img-wrapper {
            position: relative;
            width: 100%;
            max-width: 300px;
            margin: 0 auto;
        }

        .about-img {
            width: 100%;
            border-radius: 5px;
            position: relative;
            z-index: 2;
            filter: grayscale(100%) contrast(1.1);
            transition: filter 0.3s;
            border: 2px solid var(--bg-card);
        }

        .about-img-wrapper:hover .about-img { filter: none; }

        /* .about-img-wrapper::after {
            content: '';
            position: absolute;
            top: 20px;
            left: 20px;
            width: 100%;
            height: 100%;
            border: 2px solid var(--accent);
            border-radius: 5px;
            z-index: 1;
            transition: transform 0.3s;
        }

        .about-img-wrapper:hover::after { transform: translate(-10px, -10px); } */

        /* --- PROJECTS SECTION --- */
        .project-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
            gap: 25px;
        }

        .project-card {
            background-color: var(--bg-card);
            padding: 2rem 1.75rem 5rem 1.75rem;
            border-radius: 5px;
            transition: transform 0.3s, background-color 0.3s;
            display: flex;
            flex-direction: column;
            height: 100%;
            position: relative;
            overflow: hidden;
        }

        .project-card:hover {
            transform: translateY(-7px);
            background-color: var(--bg-card-hover);
        }

        .project-top {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 30px;
        }

        .folder-icon { font-size: 40px; color: var(--accent); }
        
        .project-links a {
            color: var(--text-main);
            font-size: 1.2rem;
            margin-left: 10px;
        }
        .project-links a:hover { color: var(--accent); }

        .project-card h3 {
            margin-bottom: 10px;
            font-size: 1.4rem;
            color: var(--text-main);
        }
        
        .project-card h3:hover { color: var(--accent); }

        .project-card p {
            color: var(--text-muted);
            font-size: 1rem;
            margin-bottom: 20px;
            flex-grow: 1;
        }
        
        .tech-stack {
            display: flex;
            flex-wrap: wrap;
            gap: 15px;
            font-size: 0.8rem;
            font-family: 'Fira Code', monospace;
            color: var(--text-muted);
            position: absolute;
            bottom: 2rem;
            left: 1.75rem;
            right: 1.75rem;
        }

        /* --- CONTACT SECTION --- */
        .contact { text-align: center; padding-bottom: 100px; max-width: 600px; }
        .contact h2 { font-size: 3rem; margin-bottom: 20px; }
        .contact p { color: var(--text-muted); margin-bottom: 50px; font-size: 1.1rem; }

        /* --- ANIMATIONS --- */
        .hidden { opacity: 0; transform: translateY(30px); transition: all 0.8s cubic-bezier(0.645, 0.045, 0.355, 1); }
        .show { opacity: 1; transform: translateY(0); }

        /* Staggered delays for children */
        .stagger-1 { transition-delay: 100ms; }
        .stagger-2 { transition-delay: 200ms; }
        .stagger-3 { transition-delay: 300ms; }
        .stagger-4 { transition-delay: 400ms; }

        /* Typing Cursor */
        .typing-cursor::after {
            content: '|';
            animation: blink 1s step-start infinite;
        }

        @keyframes blink { 50% { opacity: 0; } }

        /* --- RESPONSIVE --- */
        @media (max-width: 768px) {
            .hero h1 { font-size: 3rem; }
            .hero h2 { font-size: 2.5rem; }
            .about-content { grid-template-columns: 1fr; }
            .about-img-wrapper { margin: 50px auto 0; }
            .nav-links { display: none; } 
            .section-header::after { width: 100px; }
        }