<ul class="sdrop">
  <li class="nav-item dropdown">
    <a class="nav-link dropdown-toggle" href="#" title="More Info" id="navbarDropdown2" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">More Info</a>
    <div class="dropdown-menu">
      <form>
        <div class="input-group">
          <div class="form-outline w-auto">
            <input type="search" id="form1" class="form-control-dropdown" />
            <label class="form-label" for="form1">Search</label>
          </div>
        </div>
      </form>
      <a class="dropdown-item" href="" title="">Menu item 1</a>
      <a class="dropdown-item" href="" title="">Menu item 2</a>
      <a class="dropdown-item" href="" title="">Menu item 3</a>
      <a class="dropdown-item" href="" title="">Menu item 4</a>
    </div>
  </li>
</ul>

body {
  background: #ccc;
}
ul.sdrop {
  list-style: none;
  background: #000;
  color: #fff;
}

.sdrop a{
  color:#fff;
}
.sdrop a:hover{
  color:#e0dcdc
}
.sdrop .dropdown-menu {padding-top:0;padding-bottom:0;}
.sdrop .dropdown-menu a{
 padding:.5rem ;
 color:#000;
 background:#f9f9f9;
}
.sdrop .dropdown-menu a:hover{
  background:#666;
  color:#fff;
}

.sdrop .input-group{
  background:#000;
  width:auto;
  padding:.5rem;
  color:#fff;
}