menu.php

<nav class="navbar navbar-expand-lg navbar-dark bg-dark">
   <a class="navbar-brand">
      <img src="images/blood.png" width="25" alt="" class="d-inline-block align-middle mr-2">
      <span class="text-uppercase font-weight-bold">Blood Donation</span>
      <img src="images/blood.png" width="25" alt="" class="d-inline-block align-middle ml-2">
    </a>
  <button class="navbar-toggler mt-1" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>

  <div class="collapse navbar-collapse" id="navbarSupportedContent">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active py-0">
        <a class="nav-link" href="home.php">Home<span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item active py-0">
        <a class="nav-link" href="about.php">About us</a>
      </li>
      <li class="nav-item active py-0">
        <a class="nav-link" href="contact.php">Contact us</a>
      </li>
    </ul>
    <ul class="navbar-nav mr-5">
      <li class="nav-item dropdown py-0">
        <a class="nav-link dropdown-toggle" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
        </a>
        <div class="dropdown-menu" aria-labelledby="navbarDropdown">
          <a class="dropdown-item" href="userlogin.php">User Login</a>
          <a class="dropdown-item" href="adminlogin.php">Admin login</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="Sign up.php">Sign up</a>
        </div>
      </li>
    </ul>
  </div>
</nav>