tem">
  <div class="sidebar-item-container"> 
  <a href="./IntroLean.html" class="sidebar-item-text sidebar-link">Introduction to Lean</a>
  </div>
</li>
        <li class="sidebar-item">
  <div class="sidebar-item-container"> 
  <a href="./Chap3.html" class="sidebar-item-text sidebar-link"><span class="chapter-number">3</span>&nbsp; <span class="chapter-title">Proofs</span></a>
  </div>
</li>
        <li class="sidebar-item">
  <div class="sidebar-item-container"> 
  <a href="./Chap4.html" class="sidebar-i