function openProperty(evt, property) {
    var i, tabcontent, tablinks;
    tabcontent = document.getElementsByClassName("tabcontent");
    for (i = 0; i < tabcontent.length; i++) {
        tabcontent[i].style.display = "none";
    }
    tablinks = document.getElementsByClassName("tablinks");
    for (i = 0; i < tablinks.length; i++) {
        tablinks[i].className = tablinks[i].className.replace(" active", "");
    }
    document.getElementById(property).style.display = "block";
    evt.currentTarget.className += " active";
};

<div class="oil-prop">
        <div class="tab">

          <button class="tablinks" onclick="openProperty(event, 'aroma')"><i class="icon-olive" aria-hidden="true"></i><br><span class="text-btn">aroma</span></button>
          <button class="tablinks" onclick="openProperty(event, 'flavour')"><i class="icon-drop" aria-hidden="true"></i><br><span class="text-btn">flavour</span></button>
          <button class="tablinks" onclick="openProperty(event, 'pairings')"><i class="icon-pairings" aria-hidden="true"></i><br><span class="text-btn">pairings</span></button>
          <button class="tablinks" onclick="openProperty(event, 'variety')"><i class="icon-leaf" aria-hidden="true"></i><br><span class="text-btn">variety</span></button>
        </div>

    <div id="aroma" class="tabcontent">

          <h3>Aroma</h3>
          <p>Medium-fruity with notes of <b>artichoke</b> and <b>green apple</b>.</p>
    </div>

    <div id="flavour" class="tabcontent">
          <h3>Flavour</h3>
          <p><b>Fresh fruity</b> taste with a mild <b>peppery</b> finish.</p>
    </div>
    <div id="pairings" class="tabcontent">
          <h3>Pairings</h3>
          <p>Ideal with meat and fish. Goes well with vegetables, especially sweeter-tasting ones.</p>
    </div>

    <div id="variety" class="tabcontent">
          <h3>Olive Varieties</h3>
          <p><b>Leccino, Pendolino and Leccio del Corno</b></p>
    </div>
    <div class="divider-prop">
    </div>
    <div id="tab-bg-div"></div>
    <div class="border-prop"></div>
</div>