:root {
            --color-primary: #2196F3;
            --color-primary-dark: #1565C0;
            --color-accent: #00BCD4;
            --color-accent-light: #4DD0E1;
            --color-bg-dark: #0F1419;
            --color-bg-secondary: #1A2332;
            --color-bg-tertiary: #2D3A4F;
            --color-text-primary: #E8EAED;
            --color-text-secondary: #B0BEC5;
            --color-border: #37474F;
            --color-success: #4CAF50;
            --color-warning: #FF9800;
            --space-xs: 0.5rem;
            --space-sm: 1rem;
            --space-md: 1.5rem;
            --space-lg: 2rem;
            --space-xl: 3rem;
            --radius-sm: 6px;
            --radius-md: 10px;
            --radius-lg: 16px;
            --shadow-sm: 0 2px 8px rgba(0,0,0,0.3);
            --shadow-md: 0 8px 24px rgba(0,0,0,0.4);
            --shadow-lg: 0 16px 48px rgba(0,0,0,0.5);
            --transition-fast: 150ms cubic-bezier(0.16, 1, 0.3, 1);
            --transition-normal: 300ms cubic-bezier(0.16, 1, 0.3, 1);
        }

        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        html {
            scroll-behavior: smooth;
        }

        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', sans-serif;
            background: linear-gradient(135deg, var(--color-bg-dark) 0%, var(--color-bg-secondary) 100%);
            color: var(--color-text-primary);
            line-height: 1.6;
            overflow-x: hidden;
        }

        /* Header & Navigation */
        header {
            position: fixed;
            top: 0;
            left: 0;
            right: 0;
            background: rgba(15, 20, 25, 0.95);
            backdrop-filter: blur(10px);
            border-bottom: 1px solid var(--color-border);
            z-index: 1000;
            padding: var(--space-md) var(--space-lg);
            box-shadow: 0 4px 12px rgba(0,0,0,0.3);
        }

        .header-container {
            max-width: 1200px;
            margin: 0 auto;
            display: flex;
            justify-content: space-between;
            align-items: center;
            gap: var(--space-lg);
        }

        .logo {
            font-size: 1.5rem;
            font-weight: 700;
            color: var(--color-accent);
            text-decoration: none;
            letter-spacing: 1px;
        }

        .nav-wrapper {
            display: flex;
            align-items: center;
            gap: var(--space-lg);
        }

        nav {
            display: flex;
            gap: var(--space-lg);
        }

        nav a {
            color: var(--color-text-secondary);
            text-decoration: none;
            font-weight: 500;
            position: relative;
            transition: color var(--transition-fast);
        }

        nav a::after {
            content: '';
            position: absolute;
            bottom: -4px;
            left: 0;
            width: 0;
            height: 2px;
            background: var(--color-accent);
            transition: width var(--transition-normal);
        }

        nav a:hover {
            color: var(--color-accent);
        }

        nav a:hover::after {
            width: 100%;
        }

        .language-selector {
            display: flex;
            gap: var(--space-sm);
            align-items: center;
            border-left: 1px solid var(--color-border);
            padding-left: var(--space-lg);
        }

        .lang-btn {
            background: none;
            border: none;
            color: var(--color-text-secondary);
            cursor: pointer;
            font-weight: 500;
            padding: var(--space-xs) var(--space-sm);
            border-radius: var(--radius-sm);
            transition: all var(--transition-fast);
        }

        .lang-btn.active {
            background: rgba(0, 188, 212, 0.2);
            color: var(--color-accent);
        }

        .lang-btn:hover {
            color: var(--color-accent);
        }

        /* Hero Section */
        .hero {
            margin-top: 70px;
            padding: var(--space-xl) var(--space-lg);
            min-height: 100vh;
            display: flex;
            align-items: center;
            justify-content: center;
            background: linear-gradient(135deg, rgba(33, 150, 243, 0.1) 0%, rgba(0, 188, 212, 0.1) 100%);
            position: relative;
            overflow: hidden;
        }

        .hero::before {
            content: '';
            position: absolute;
            top: -50%;
            right: -50%;
            width: 1000px;
            height: 1000px;
            background: radial-gradient(circle, rgba(0, 188, 212, 0.15) 0%, transparent 70%);
            border-radius: 50%;
            animation: float 20s ease-in-out infinite;
        }

        @keyframes float {
            0%, 100% { transform: translate(0, 0); }
            50% { transform: translate(30px, 30px); }
        }

        .hero-content {
            max-width: 900px;
            text-align: center;
            position: relative;
            z-index: 2;
            display: flex;
            flex-direction: column;
            align-items: center;
            gap: var(--space-lg);
        }

        .hero-image {
            width: 200px;
            height: 200px;
            border-radius: 50%;
            object-fit: cover;
            border: 4px solid var(--color-accent);
            box-shadow: 0 0 30px rgba(0, 188, 212, 0.4);
            transition: transform var(--transition-normal), box-shadow var(--transition-normal);
        }

        .hero-image:hover {
            transform: scale(1.05);
            box-shadow: 0 0 40px rgba(0, 188, 212, 0.6);
        }

        .hero h1 {
            font-size: 4rem;
            font-weight: 800;
            margin-bottom: var(--space-md);
            background: linear-gradient(135deg, var(--color-accent-light) 0%, var(--color-primary) 100%);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            background-clip: text;
            line-height: 1.1;
        }

        .hero .subtitle {
            font-size: 1.3rem;
            color: var(--color-text-secondary);
            margin-bottom: var(--space-md);
            font-weight: 300;
            max-width: 700px;
            margin-left: auto;
            margin-right: auto;
        }

        .hero .description {
            font-size: 1rem;
            color: var(--color-text-secondary);
            max-width: 600px;
            margin: var(--space-lg) auto var(--space-xl);
            line-height: 1.8;
        }

        .cta-buttons {
            display: flex;
            gap: var(--space-md);
            justify-content: center;
            flex-wrap: wrap;
        }

        .btn {
            padding: var(--space-md) var(--space-lg);
            border: none;
            border-radius: var(--radius-md);
            font-size: 1rem;
            font-weight: 600;
            cursor: pointer;
            transition: all var(--transition-normal);
            text-decoration: none;
            display: inline-flex;
            align-items: center;
            gap: var(--space-sm);
        }

        .btn-primary {
            background: linear-gradient(135deg, var(--color-accent) 0%, var(--color-primary) 100%);
            color: var(--color-bg-dark);
        }

        .btn-primary:hover {
            box-shadow: 0 8px 20px rgba(0, 188, 212, 0.4);
            transform: translateY(-2px);
        }

        .btn-secondary {
            background: transparent;
            border: 2px solid var(--color-accent);
            color: var(--color-accent);
        }

        .btn-secondary:hover {
            background: rgba(0, 188, 212, 0.1);
            transform: translateY(-2px);
        }

        /* Main Content */
        main {
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 var(--space-lg);
        }

        section {
            padding: var(--space-xl) 0;
            border-bottom: 1px solid var(--color-border);
        }

        section:last-child {
            border-bottom: none;
        }

        .section-title {
            font-size: 3rem;
            font-weight: 700;
            margin-bottom: var(--space-lg);
            position: relative;
            padding-bottom: var(--space-md);
        }

        .section-title::after {
            content: '';
            position: absolute;
            bottom: 0;
            left: 0;
            width: 60px;
            height: 4px;
            background: linear-gradient(135deg, var(--color-accent) 0%, var(--color-primary) 100%);
            border-radius: 2px;
        }

        .section-subtitle {
            color: var(--color-text-secondary);
            font-size: 1.1rem;
            margin-bottom: var(--space-xl);
        }

        /* Education Section */
        .education-card {
            background: var(--color-bg-secondary);
            border: 1px solid var(--color-border);
            border-radius: var(--radius-lg);
            padding: var(--space-lg);
            margin-bottom: var(--space-lg);
            transition: all var(--transition-normal);
            border-left: 4px solid var(--color-accent);
        }

        .education-card:hover {
            background: var(--color-bg-tertiary);
            box-shadow: var(--shadow-md);
            transform: translateX(4px);
        }

        .education-card h3 {
            font-size: 1.4rem;
            color: var(--color-accent);
            margin-bottom: var(--space-xs);
        }

        .education-card .institution {
            color: var(--color-text-secondary);
            font-weight: 500;
            margin-bottom: var(--space-xs);
        }

        .education-card .period {
            color: var(--color-text-secondary);
            font-size: 0.9rem;
            margin-top: var(--space-md);
        }

        /* Projects Section */
        .projects-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
            gap: var(--space-lg);
            margin-bottom: var(--space-xl);
        }

        .project-card {
            background: var(--color-bg-secondary);
            border: 1px solid var(--color-border);
            border-radius: var(--radius-lg);
            padding: var(--space-lg);
            transition: all var(--transition-normal);
            display: flex;
            flex-direction: column;
            height: 100%;
            position: relative;
            overflow: hidden;
        }

        .project-card::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            height: 3px;
            background: linear-gradient(90deg, var(--color-accent), var(--color-primary));
            transform: scaleX(0);
            transform-origin: left;
            transition: transform var(--transition-normal);
        }

        .project-card:hover {
            background: var(--color-bg-tertiary);
            box-shadow: var(--shadow-lg);
            transform: translateY(-8px);
        }

        .project-card:hover::before {
            transform: scaleX(1);
        }

        .project-card h3 {
            font-size: 1.3rem;
            color: var(--color-accent);
            margin-bottom: var(--space-sm);
        }

        .project-card p {
            color: var(--color-text-secondary);
            margin-bottom: var(--space-md);
            flex-grow: 1;
            line-height: 1.7;
        }

        .project-meta {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-top: var(--space-md);
            padding-top: var(--space-md);
            border-top: 1px solid var(--color-border);
        }

        .tech-tags {
            display: flex;
            flex-wrap: wrap;
            gap: var(--space-xs);
        }

        .tech-tag {
            background: rgba(0, 188, 212, 0.2);
            color: var(--color-accent-light);
            padding: var(--space-xs) var(--space-sm);
            border-radius: var(--radius-sm);
            font-size: 0.8rem;
            font-weight: 500;
            border: 1px solid rgba(0, 188, 212, 0.3);
        }

        .project-link {
            color: var(--color-accent);
            text-decoration: none;
            font-weight: 600;
            display: inline-flex;
            align-items: center;
            gap: 4px;
            transition: gap var(--transition-fast);
        }

        .project-link:hover {
            gap: 8px;
        }

        /* Skills Section */
        .skills-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
            gap: var(--space-lg);
        }

        .skill-category {
            background: var(--color-bg-secondary);
            border: 1px solid var(--color-border);
            border-radius: var(--radius-lg);
            padding: var(--space-lg);
            transition: all var(--transition-normal);
        }

        .skill-category:hover {
            background: var(--color-bg-tertiary);
            box-shadow: var(--shadow-md);
            border-color: var(--color-accent);
        }

        .skill-category h4 {
            color: var(--color-accent);
            font-size: 1.2rem;
            margin-bottom: var(--space-md);
            display: flex;
            align-items: center;
            gap: var(--space-sm);
        }

        .skill-list {
            list-style: none;
        }

        .skill-list li {
            padding: var(--space-xs) 0;
            color: var(--color-text-secondary);
            display: flex;
            align-items: center;
            gap: var(--space-sm);
        }

        .skill-list li::before {
            content: '▸';
            color: var(--color-accent);
            font-weight: bold;
        }

        /* Contact Section */
        .contact-container {
            background: var(--color-bg-secondary);
            border: 1px solid var(--color-border);
            border-radius: var(--radius-lg);
            padding: var(--space-xl);
            text-align: center;
        }

        .contact-text {
            color: var(--color-text-secondary);
            font-size: 1.1rem;
            margin-bottom: var(--space-lg);
            max-width: 600px;
            margin-left: auto;
            margin-right: auto;
        }

        .contact-links {
            display: flex;
            justify-content: center;
            gap: var(--space-lg);
            flex-wrap: wrap;
            margin-bottom: var(--space-lg);
        }

        .contact-link {
            color: var(--color-accent);
            text-decoration: none;
            font-weight: 600;
            transition: all var(--transition-fast);
            display: inline-flex;
            align-items: center;
            gap: var(--space-xs);
        }

        .contact-link:hover {
            color: var(--color-accent-light);
            transform: translateY(-2px);
        }

        /* Footer */
        footer {
            background: var(--color-bg-secondary);
            border-top: 1px solid var(--color-border);
            padding: var(--space-lg);
            text-align: center;
            color: var(--color-text-secondary);
            margin-top: var(--space-xl);
        }

        .footer-content {
            max-width: 1200px;
            margin: 0 auto;
        }

        .hidden {
            display: none;
        }

        /* Responsive */
        @media (max-width: 768px) {
            .hero h1 {
                font-size: 2.5rem;
            }

            .hero .subtitle {
                font-size: 1.1rem;
            }

            .hero-image {
                width: 150px;
                height: 150px;
            }

            nav {
                gap: var(--space-md);
            }

            nav a {
                font-size: 0.9rem;
            }

            .language-selector {
                border-left: none;
                padding-left: 0;
            }

            .section-title {
                font-size: 2rem;
            }

            .projects-grid {
                grid-template-columns: 1fr;
            }

            .skills-grid {
                grid-template-columns: 1fr;
            }

            .cta-buttons {
                flex-direction: column;
                align-items: center;
            }

            .btn {
                width: 100%;
                max-width: 300px;
                justify-content: center;
            }

            .header-container {
                flex-direction: column;
                gap: var(--space-md);
            }

            .nav-wrapper {
                flex-direction: column;
                width: 100%;
            }

            nav {
                flex-direction: column;
                width: 100%;
            }

            nav a {
                width: 100%;
                text-align: center;
            }
        }

        @media (max-width: 480px) {
            header {
                padding: var(--space-sm) var(--space-md);
            }

            .logo {
                font-size: 1.2rem;
            }

            nav {
                gap: var(--space-sm);
            }

            nav a {
                font-size: 0.8rem;
            }

            .hero {
                padding: var(--space-lg) var(--space-md);
                min-height: auto;
                padding-top: 100px;
            }

            .hero h1 {
                font-size: 2rem;
            }

            .hero-image {
                width: 120px;
                height: 120px;
            }

            main {
                padding: 0 var(--space-md);
            }

            section {
                padding: var(--space-lg) 0;
            }

            .section-title {
                font-size: 1.5rem;
            }

            .education-card,
            .project-card,
            .skill-category,
            .contact-container {
                padding: var(--space-md);
            }
        }