JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://semantic-ui.com/build/packaged/css/semantic.min.css">
    <div class="ui page grid">
      <header class="sixteen wide column">
        <div class="ui segment">Header text.</div>
      </header>
      <div class="ui divided grid">
        <div class="eight wide column">
          <div class="ui segment">Left text</div>
        </div>
        <div class="eight wide column">
          <div class="ui segment">Right text</div>
        </div>
      </div>
      <div class="sixteen wide column">
        <div class="ui three column grid">
          <div class="column">
            <div class="ui segment">1</div>
          </div>
          <div class="column">
            <div class="ui segment">2</div>
          </div>
          <div class="column">
            <div class="ui segment">3</div>
          </div>
        </div>
      </div>
      <footer class="sixteen wide column">
        <div class="ui segment">Footer text.</div>
      </footer>
    </div>

CSS

.ui.page.grid > .sixteen.wide.column > .ui.three.column.grid > .column {
    margin-top: 0px;
    margin-bottom: 0px;
}