Dear fodxp

Please take a look at the below code. What I have changed there?
- Added mt-0 mb-0 classes to the .md-form div,
- added .indigo class to the *dropdownMenu div,
- added .text-white classes to the a.dropdown-item,
- changed the padding of the .navbar class,
- changed the font-size of the .navbar-nav class

Now the whole navbar has 41.5px height.

.scss:

.navbar {
padding: 0 1rem;
}

.navbar-nav {
font-size: 0.8rem;
}

.html:

<mdb-navbar SideClass="navbar navbar-expand-lg navbar-dark indigo">
  <mdb-navbar-brand>
    <a class="navbar-brand" href="#">
      <img src="https://mdbootstrap.com/img/logo/mdb-transparent.png" height="30" alt="">
    </a>
  </mdb-navbar-brand>

  <!-- Collapsible content -->
  <links>

    <!-- Links -->
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link waves-light" mdbWavesEffect>Home<span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link waves-light" mdbWavesEffect>Features</a>
      </li>
      <li class="nav-item">
        <a class="nav-link waves-light" mdbWavesEffect>Pricing</a>
      </li>

      <!-- Dropdown -->
      <li class="nav-item dropdown" dropdown>
        <a dropdownToggle mdbWavesEffect type="button" class="nav-link dropdown-toggle waves-light" mdbWavesEffect>
          Basic dropdown<span class="caret"></span></a>
        <div *dropdownMenu class="dropdown-menu dropdown dropdown-primary indigo " role="menu">
          <a class="dropdown-item waves-light text-white" mdbWavesEffect href="#">Action</a>
          <a class="dropdown-item waves-light text-white" mdbWavesEffect href="#">Another action</a>
          <a class="dropdown-item waves-light text-white" mdbWavesEffect href="#">Something else here</a>
          <div class="divider dropdown-divider"></div>
          <a class="dropdown-item waves-light text-white" mdbWavesEffect href="#">Separated link</a>
        </div>
      </li>

    </ul>
    <!-- Links -->

    <form class="form-inline">
      <div class="md-form mt-0 mb-0">
        <input class="form-control mr-sm-2" type="text" placeholder="Search">
      </div>
    </form>

  </links>
  <!-- Collapsible content -->
</mdb-navbar>

Best Regards,

Damian