:root {
            --bg-primary: #ffffff;
            --bg-secondary: #f8f9fa;
            --text-primary: #212529;
            --text-secondary: #6c757d;
            --accent: #0d6efd;
            --accent-hover: #0b5ed7;
            --border-color: #dee2e6;
            --transition: all 0.3s ease;
        }

        [data-theme="dark"] {
            --bg-primary: #121212;
            --bg-secondary: #1e1e1e;
            --text-primary: #f8f9fa;
            --text-secondary: #a0a0a0;
            --accent: #375a7f;
            --accent-hover: #2b4764;
            --border-color: #333333;
        }

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

        html {
            scroll-behavior: smooth;
        }

        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            background-color: var(--bg-primary);
            color: var(--text-primary);
            line-height: 1.6;
            transition: var(--transition);
        }

        section {
            padding: 5rem 2rem;
            max-width: 1100px;
            margin: 0 auto;
        }

        .section-title {
            text-align: center;
            margin-bottom: 3rem;
            font-size: 2.5rem;
            position: relative;
        }

        .section-title::after {
            content: '';
            display: block;
            width: 50px;
            height: 4px;
            background-color: var(--accent);
            margin: 10px auto 0;
            border-radius: 2px;
        }

        /* --- Navigation --- */
        header {
            position: fixed;
            top: 0;
            width: 100%;
            background-color: var(--bg-primary);
            border-bottom: 1px solid var(--border-color);
            z-index: 1000;
            transition: var(--transition);
        }

        nav {
            display: flex;
            justify-content: space-between;
            align-items: center;
            max-width: 1100px;
            margin: 0 auto;
            padding: 1rem 2rem;
        }

        .logo {
            font-size: 1.5rem;
            font-weight: bold;
            color: var(--accent);
            text-decoration: none;
        }

        .nav-links {
            display: flex;
            list-style: none;
            gap: 2rem;
            align-items: center;
        }

        .nav-links a {
            text-decoration: none;
            color: var(--text-primary);
            font-weight: 500;
            transition: var(--transition);
        }

        .nav-links a:hover, .nav-links a.active {
            color: var(--accent);
        }

        .theme-toggle {
            background: none;
            border: 1px solid var(--border-color);
            padding: 0.5rem 1rem;
            cursor: pointer;
            border-radius: 20px;
            color: var(--text-primary);
            font-size: 0.9rem;
            transition: var(--transition);
        }

        .theme-toggle:hover {
            background-color: var(--bg-secondary);
        }

        /* --- Hero Section --- */
        #hero {
            display: flex;
            flex-direction: column;
            justify-content: center;
            align-items: center;
            text-align: center;
            min-height: 100vh;
            padding-top: 80px;
        }

        #hero h1 {
            font-size: 3.5rem;
            margin-bottom: 1rem;
        }

        #hero h1 span {
            color: var(--accent);
        }

        #hero p {
            font-size: 1.25rem;
            color: var(--text-secondary);
            margin-bottom: 2rem;
            max-width: 600px;
        }

        .btn {
            display: inline-block;
            background-color: var(--accent);
            color: white;
            padding: 0.75rem 1.5rem;
            text-decoration: none;
            border-radius: 5px;
            font-weight: 500;
            transition: var(--transition);
            border: none;
            cursor: pointer;
        }

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

        /* --- Portfolio/Projects Section --- */
        .filter-buttons {
            display: flex;
            justify-content: center;
            gap: 1rem;
            margin-bottom: 2rem;
        }

        .filter-btn {
            background: none;
            border: 1px solid var(--border-color);
            padding: 0.5rem 1rem;
            border-radius: 4px;
            cursor: pointer;
            color: var(--text-primary);
            transition: var(--transition);
        }

        .filter-btn.active, .filter-btn:hover {
            background-color: var(--accent);
            color: white;
            border-color: var(--accent);
        }

        .projects-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(300px, 11fr));
            gap: 2rem;
        }

        .project-card {
            background-color: var(--bg-secondary);
            border: 1px solid var(--border-color);
            border-radius: 8px;
            overflow: hidden;
            transition: var(--transition);
        }

        .project-card:hover {
            transform: translateY(-5px);
        }

        .project-info {
            padding: 1.5rem;
        }

        .project-info h3 {
            margin-bottom: 0.5rem;
        }

        .project-info p {
            color: var(--text-secondary);
            font-size: 0.95rem;
            margin-bottom: 1rem;
        }

        .tag {
            display: inline-block;
            background-color: var(--border-color);
            color: var(--text-primary);
            font-size: 0.8rem;
            padding: 0.2rem 0.5rem;
            border-radius: 4px;
            margin-right: 0.5rem;
        }

        /* --- Contact Section --- */
        .contact-container {
            max-width: 600px;
            margin: 0 auto;
        }

        .form-group {
            margin-bottom: 1.5rem;
        }

        .form-group label {
            display: block;
            margin-bottom: 0.5rem;
            font-weight: 500;
        }

        .form-control {
            width: 100%;
            padding: 0.75rem;
            border: 1px solid var(--border-color);
            border-radius: 5px;
            background-color: var(--bg-primary);
            color: var(--text-primary);
            font-size: 1rem;
        }

        .form-control:focus {
            outline: none;
            border-color: var(--accent);
        }

        .error-message {
            color: #dc3545;
            font-size: 0.85rem;
            margin-top: 0.25rem;
            display: none;
        }

        /* --- Footer --- */
        footer {
            text-align: center;
            padding: 2rem;
            border-top: 1px solid var(--border-color);
            color: var(--text-secondary);
            font-size: 0.9rem;
        }

        /* --- Responsive Design --- */
        @media (max-width: 768px) {
            .nav-links {
                gap: 1rem;
            }
            #hero h1 {
                font-size: 2.5rem;
            }
        }