class PumpHeader extends HTMLElement {
  connectedCallback() {
    this.attachShadow({ mode: 'open' });
    this.shadowRoot.innerHTML = `
      <style>
        :host {
          display: block;
          width: 100%;
        }
        header {
          background-color: rgba(15, 23, 42, 0.8);
          backdrop-filter: blur(8px);
          padding: 1rem 2rem;
          border-bottom: 1px solid rgba(255, 255, 255, 0.1);
          position: sticky;
          top: 0;
          z-index: 50;
        }
        .container {
          max-width: 1280px;
          margin: 0 auto;
          display: flex;
          justify-content: space-between;
          align-items: center;
        }
        .logo {
          display: flex;
          align-items: center;
          gap: 0.75rem;
          font-weight: 700;
          font-size: 1.25rem;
          color: #ef4444;
          text-decoration: none;
        }
        .logo:hover {
          color: #f87171;
        }
        nav ul {
          display: flex;
          gap: 1.5rem;
          list-style: none;
        }
        nav a {
          color: #e2e8f0;
          text-decoration: none;
          font-weight: 500;
          display: flex;
          align-items: center;
          gap: 0.5rem;
          transition: color 0.2s;
        }
        nav a:hover {
          color: #ef4444;
        }
        .mobile-menu-button {
          display: none;
          background: none;
          border: none;
          color: #e2e8f0;
          cursor: pointer;
        }
        @media (max-width: 768px) {
          .mobile-menu-button {
            display: block;
          }
          nav {
            position: absolute;
            top: 100%;
            left: 0;
            right: 0;
            background-color: #0f172a;
            padding: 1rem;
            display: none;
            flex-direction: column;
            border-bottom: 1px solid rgba(255, 255, 255, 0.1);
          }
          nav.active {
            display: flex;
          }
          nav ul {
            flex-direction: column;
            gap: 0.75rem;
          }
        }
      </style>
      <header>
        <div class="container">
          <a href="index.html" class="logo">
            <i data-feather="activity"></i>
            <span>Pump Doctor Pro</span>
          </a>
          
          <button class="mobile-menu-button">
            <i data-feather="menu"></i>
          </button>
          
          <nav>
            <ul>
              <li><a href="calculator.html"><i data-feather="calculator"></i> Calculator</a></li>
              <li><a href="diagnosis.html"><i data-feather="alert-triangle"></i> Diagnosis</a></li>
              <li><a href="database.html"><i data-feather="database"></i> Database</a></li>
              <li>
                <button id="themeToggle" class="flex items-center gap-2 text-current">
                  <i data-feather="moon"></i>
                  <span>Dark Mode</span>
                </button>
              </li>
            </ul>
          </nav>
        </div>
      </header>
    `;

    const mobileMenuButton = this.shadowRoot.querySelector('.mobile-menu-button');
    const nav = this.shadowRoot.querySelector('nav');
    const themeToggle = this.shadowRoot.getElementById('themeToggle');
    
    mobileMenuButton.addEventListener('click', () => {
      nav.classList.toggle('active');
    });
    
    themeToggle.addEventListener('click', () => {
      const html = document.documentElement;
      html.classList.toggle('dark');
      localStorage.setItem('darkMode', html.classList.contains('dark'));
      
      const icon = themeToggle.querySelector('i');
      if (html.classList.contains('dark')) {
        icon.setAttribute('data-feather', 'moon');
        themeToggle.querySelector('span').textContent = 'Dark Mode';
      } else {
        icon.setAttribute('data-feather', 'sun');
        themeToggle.querySelector('span').textContent = 'Light Mode';
      }
      feather.replace();
    });
    
    // Initialize feather icons
    feather.replace();
  }
}

customElements.define('pump-header', PumpHeader);