Андрей

<div class="main_container uk-container">
   <div class="uk-child-width-1-2 uk-child-width-1-3@s ..." uk-grid>
      ...

uk-card uk-card-default uk-child-width-1-2 uk-grid uk-grid-collapse

<ul class="uk-navbar-nav" uk-scrollspy-nav="closest: li; scroll: true">
    <li><a href="#a">A</a></li>
    <li><a href="#b">B</a></li>
    <li><a href="#c">C</a></li>
</ul>

.uk-tooltip::after {
    bottom: 100%;
    right: 4%;
    border: solid transparent;
    content: '';
    height: 0;
    width: 0;
    position: absolute;
    pointer-events: none;
    border-color: rgba(255, 255, 255, 0);
    border-bottom-color: #ffffff;
    border-width: 6px;
    margin-left: -6px;
}

.uk-navbar-nav>li>a {
    min-height: 40px; /* уменьшили высоту */
}

.uk-navbar-item, .uk-navbar-nav>li>a, .uk-navbar-toggle {
   min-height: 40px; 
}