Read below codes carefully. just read and understand.

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Professional Portfolio</title>
    <style>
        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            margin: 0;
            padding: 0;
            display: flex;
            height: 100vh;
            overflow: hidden;
            background-color: #f0f2f5;
            color: #333;
        }

        .sidebar {
            width: 260px;
            background-color: #2c3e50;
            color: #ecf0f1;
            display: flex;
            flex-direction: column;
            box-shadow: 2px 0 5px rgba(0, 0, 0, 0.1);
            position: fixed;
            height: 100vh;
        }

        .sidebar h2 {
            text-align: center;
            padding: 20px;
            border-bottom: 1px solid #34495e;
            font-weight: 600;
            letter-spacing: 1px;
        }

        .sidebar nav a {
            padding: 15px 20px;
            text-decoration: none;
            color: #ecf0f1;
            display: block;
            transition: background-color 0.3s, color 0.3s;
            font-size: 16px;
            cursor: pointer;
        }

        .sidebar nav a:hover {
            background-color: #34495e;
            color: #ecdbff;
        }

        .main-content {
            flex: 1;
            padding: 40px;
            overflow-y: auto;
            display: none;
            margin-left: 260px;
            transition: opacity 0.3s;
        }

        .section {
            background-color: #fff;
            margin-bottom: 40px;
            padding: 30px;
            border-radius: 10px;
            box-shadow: 0 4px 8px rgba(0, 0, 0, 0.15);
        }

        .section h3 {
            margin-top: 0;
            font-size: 24px;
            color: #34495e;
            border-bottom: 2px solid #ecf0f1;
            padding-bottom: 10px;
        }

        .section p, .section ul {
            line-height: 1.6;
            font-size: 18px;
        }

        .footer {
            text-align: center;
            padding: 20px;
            color: #333;
            position: absolute;
            bottom: 0;
            width: calc(100% - 260px);
            box-sizing: border-box;
            font-size: 14px;
            margin-left: 260px;
            background: transparent;
        }

        .active {
            display: block; /* Show active section */
            opacity: 1;
        }

        ul {
            list-style-type: none;
            padding: 0;
        }

        ul li {
            margin-bottom: 10px;
        }

        /* Responsive Design */
        @media (max-width: 768px) {
            .sidebar {
                width: 100%;
                height: auto;
                position: relative;
                display: flex;
                flex-direction: row;
                overflow-x: auto;
            }

            .sidebar h2 {
                flex: 1 0 auto;
            }

            .sidebar nav {
                display: flex;
                flex: 1 1 auto;
            }

            .sidebar nav a {
                flex: 1;
                padding: 15px;
                text-align: center;
            }

            .main-content {
                margin-left: 0;
                margin-top: 20px;
            }

            .footer {
                width: 100%;
                margin-left: 0;
            }
        }
    </style>
</head>
<body>

    <div class="sidebar">
        <h2>My Portfolio</h2>
        <nav>
            <a onclick="showSection('about')">About Me</a>
            <a onclick="showSection('projects')">Projects</a>
            <a onclick="showSection('skills')">Skills</a>
            <a onclick="showSection('contact')">Contact</a>
        </nav>
    </div>

    <div id="about" class="main-content active">
        <div class="section">
            <h3>About Me</h3>
            <p>Hello! I'm a passionate [Your Profession] based in [Your Location]. With a deep interest in [Field/Industry], I've honed my skills through extensive experience and dedicated practice.</p>
            <p>I strive to create impactful work that not only meets expectations but also inspires and innovates. Explore my portfolio to see examples of my commitment to excellence in action.</p>
        </div>
    </div>

    <div id="projects" class="main-content">
        <div class="section">
            <h3>Projects</h3>
            <ul>
                <li>
                    <strong>Project One:</strong> Description of project one showcasing your role and the outcome.
                </li>
                <li>
                    <strong>Project Two:</strong> Description of project two highlighting unique challenges and accomplishments.
                </li>
                <li>
                    <strong>Project Three:</strong> A brief about any significant project you want to showcase.
                </li>
                <!-- Add more projects as needed -->
            </ul>
        </div>
    </div>

    <div id="skills" class="main-content">
        <div class="section">
            <h3>Skills</h3>
            <p>Here are the skills that power my professional journey:</p>
            <ul>
                <li>Skill 1: Description or level of expertise.</li>
                <li>Skill 2: Description or level of expertise.</li>
                <li>Skill 3: Description or level of expertise.</li>
                <!-- Add more skills as needed -->
            </ul>
        </div>
    </div>

    <div id="contact" class="main-content">
        <div class="section">
            <h3>Contact</h3>
            <p>If you'd like to discuss a project, collaboration, or just want to say hi, drop a message at:</p>
            <p>Email: <a href="mailto:your.email@example.com">your.email@example.com</a></p>
            <p>LinkedIn: <a href=<PRESIDIO_ANONYMIZED_URL> target="_blank">yourprofile</a></p>
            <!-- Add more contact methods as needed -->
        </div>
    </div>

    <div class="footer">2023 &copy; Your Name | All Rights Reserved</div>

    <script>
        function showSection(sectionId) {
            // Hide all sections
            var sections = document.querySelectorAll('.main-content');
            sections.forEach(function(section) {
                section.classList.remove('active');
            });

            // Show the selected section
            var sectionToShow = document.getElementById(sectionId);
            sectionToShow.classList.add('active');
        }
    </script>

</body>
</html>