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

        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
            line-height: 1.6;
            color: #333;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            min-height: 100vh;
            padding: 1rem;
        }

        main {
            max-width: 700px;
            margin: 2rem auto;
            padding: 0 1rem;
        }

        .profile-card {
            background: white;
            border-radius: 16px;
            box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
            padding: 2rem;
            animation: fadeIn 0.6s ease-in;
        }

        @keyframes fadeIn {
            from {
                opacity: 0;
                transform: translateY(20px);
            }
            to {
                opacity: 1;
                transform: translateY(0);
            }
        }

        header {
            text-align: center;
            margin-bottom: 2rem;
            padding-bottom: 1.5rem;
            border-bottom: 3px solid #667eea;
        }

        h1 {
            font-size: clamp(1.8rem, 5vw, 2.5rem);
            color: #667eea;
            margin-bottom: 0.5rem;
        }

        header p {
            color: #666;
            font-size: clamp(0.95rem, 2vw, 1.05rem);
        }

        section {
            margin-bottom: 2rem;
        }

        h2 {
            color: #667eea;
            font-size: clamp(1.3rem, 4vw, 1.6rem);
            margin-bottom: 1.5rem;
            display: flex;
            align-items: center;
            gap: 0.5rem;
        }

        h2::before {
            content: '✉';
            font-size: 1.2em;
        }

        .form-row {
            margin-bottom: 1.5rem;
            display: flex;
            flex-direction: column;
        }

        label {
            margin-bottom: 0.5rem;
            font-weight: 600;
            color: #333;
            font-size: 0.95rem;
            display: flex;
            align-items: center;
            gap: 0.3rem;
        }

        label::after {
            content: '*';
            color: #764ba2;
            font-size: 1.1em;
        }

        input[type="text"],
        input[type="email"],
        textarea {
            padding: 0.9rem;
            border-radius: 10px;
            border: 2px solid #e0e0e0;
            font-size: 1rem;
            width: 100%;
            font-family: inherit;
            transition: all 0.3s ease;
            background: #f8f9fa;
        }

        input[type="text"]:focus,
        input[type="email"]:focus,
        textarea:focus {
            outline: none;
            border-color: #667eea;
            background: white;
            box-shadow: 0 0 0 4px rgba(102, 126, 234, 0.1);
            transform: translateY(-2px);
        }

        input[type="text"]:hover,
        input[type="email"]:hover,
        textarea:hover {
            border-color: #764ba2;
        }

        textarea {
            resize: vertical;
            min-height: 120px;
        }

        .error {
            color: #dc3545;
            font-size: 0.875rem;
            margin-top: 0.4rem;
            min-height: 1.2em;
            font-weight: 500;
            display: flex;
            align-items: center;
            gap: 0.3rem;
        }

        .error:not(:empty)::before {
            content: '⚠';
            font-size: 1em;
        }

        .success {
            margin-top: 1rem;
            color: #155724;
            background: linear-gradient(135deg, #d4edda, #c3e6cb);
            padding: 1rem;
            border-radius: 10px;
            border: 2px solid #28a745;
            display: none;
            font-weight: 500;
            animation: slideIn 0.4s ease;
        }

        @keyframes slideIn {
            from {
                opacity: 0;
                transform: translateY(-10px);
            }
            to {
                opacity: 1;
                transform: translateY(0);
            }
        }

        .success:empty {
            display: none;
        }

        .success:not(:empty) {
            display: flex;
            align-items: center;
            gap: 0.5rem;
        }

        .success:not(:empty)::before {
            content: '✓';
            font-size: 1.5em;
            color: #28a745;
        }

        button#submitBtn {
            padding: 1rem 2.5rem;
            border-radius: 50px;
            background: linear-gradient(135deg, #667eea, #764ba2);
            color: white;
            border: none;
            cursor: pointer;
            font-size: 1.05rem;
            font-weight: 600;
            width: 100%;
            transition: all 0.3s ease;
            box-shadow: 0 4px 15px rgba(102, 126, 234, 0.4);
        }

        button#submitBtn:hover {
            transform: translateY(-2px);
            box-shadow: 0 6px 20px rgba(102, 126, 234, 0.6);
        }

        button#submitBtn:active {
            transform: translateY(0);
        }

        button#submitBtn:focus {
            outline: none;
            box-shadow: 0 0 0 4px rgba(102, 126, 234, 0.3);
        }

        nav {
            text-align: center;
            margin-top: 2rem;
            padding-top: 1.5rem;
            border-top: 2px solid #f0f0f0;
        }

        .btn {
            display: inline-block;
            padding: 0.8rem 2rem;
            background: transparent;
            color: #667eea;
            text-decoration: none;
            border-radius: 50px;
            font-weight: 600;
            transition: all 0.3s ease;
            border: 2px solid #667eea;
        }

        .btn:hover {
            background: #667eea;
            color: white;
            transform: translateY(-2px);
            box-shadow: 0 4px 12px rgba(102, 126, 234, 0.3);
        }

        /* Input validation states */
        input.invalid,
        textarea.invalid {
            border-color: #dc3545;
            background: #fff5f5;
        }

        input.valid,
        textarea.valid {
            border-color: #28a745;
            background: #f0fff4;
        }

        /* Tablet styles */
        @media (min-width: 768px) {
            .profile-card {
                padding: 3rem;
            }

            button#submitBtn {
                width: auto;
                min-width: 200px;
            }

            .form-row:last-of-type {
                display: flex;
                justify-content: center;
            }
        }

        /* Desktop styles */
        @media (min-width: 1024px) {
            main {
                margin: 3rem auto;
            }

            .profile-card {
                padding: 3.5rem;
            }
        }

        /* Mobile optimization */
        @media (max-width: 480px) {
            body {
                padding: 0.5rem;
            }

            main {
                margin: 1rem auto;
            }

            .profile-card {
                padding: 1.5rem;
            }

            input[type="text"],
            input[type="email"],
            textarea {
                padding: 0.75rem;
                font-size: 16px; /* Prevents zoom on iOS */
            }
        }

        /* Loading state */
        button#submitBtn:disabled {
            opacity: 0.6;
            cursor: not-allowed;
            transform: none;
        }