<div class="button-wrap">
  <div data-destination="menu1" class="button"> <span>Show</span> <b>Hide</b> menu1</div>
  <div data-destination="menu2" class="button"><span>Show</span> <b>Hide</b> menu2</div>
  <div data-destination="menu3" class="button"><span>Show</span> <b>Hide</b> menu3</div>

  <div class="menu" id="menu1">
    This is menu1 element. This is menu1 element. This is <a href="overLink.php" class="overlink">overLink</a> in menu1 element.
  </div>

  <div class="menu menu2" id="menu2">
    This is menu2 element. This is menu2 element.
    This is menu2 element. This is menu2 element. This is <a href="overLink.php" class="overlink">overLink</a> in menu2 element.
    This is menu2 element. This is menu2 element. This is menu2 element.
    This is menu2 element. This is menu2 element. This is menu2 element. This is <a href="overLink.php" class="overlink">overLink</a> in menu2 element.
  </div>

  <div class="menu menu3" id="menu3">
    This is <a href="overLink.php" class="overlink">overLink</a> in menu3 element.
  </div>
</div>
<div class="main">
  <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents. <a href="underLink.php" class="underlink">underLink</a> This is main contents.

html {
  box-sizing: border-box;
}

*,
*:before,
*:after {
  box-sizing: inherit;
}

html,
body {
  margin: 0;
  padding: 0;
}

.button-wrap {
  position: absolute;
  max-width: 50rem;
  margin: 10px auto;
  padding: 10px;
  display: flex;
  justify-content: center;
  left: 0;
  right: 0;
  pointer-events: none;
}

.button {
  min-width: 120px;
  text-align: center;
  border-radius: 20px;
  background: red;
  color: #fff;
  padding: 5px;
  border: 1px solid #666;
  margin: 0 15px;
  pointer-events: initial;
  cursor: pointer;
}

.button:hover,
.button:focus,
.button.active {
  outline: 0;
  background: orange;
}
.button b {
  display: none;
}
.button span {
  font-weight: bold;
}
.button.active span {
  display: none;
}
.button.active b {
  display: inline-block;
}

.menu-wrap {
  position: relative;
  max-width: 50rem;
  margin: auto;
  display: flex;
  justify-content: center;
}

.menu {
  padding: 10px;
  border: 1px solid red;
  text-align: center;
  background-color: lightblue;
  margin: auto;
  transition: transform 0.3s ease;
  text-align: left;
  box-shadow: 0 0 10px 10px rgba(0, 0, 0, 0.5);
}

.menu2 {
  background-color: green;
}

.menu3 {
  background-color: cyan;
}

.menu4 {
  background-color: teal;
}

.hide {
  transform: scale(0.0001);
  opacity: 0;
  position: absolute;
  z-index: -1;
  top: 0;
}

.show {
  transform: scale(1);
  opacity: 1;
  z-index: 2;
  top: 100%;
  pointer-events: initial;
}
.overlink {
  background: blue;
  color: white;
}
.underlink {
  background: green;
  color: white;
}

(function (d) {
  "use strict";

  const buttons = d.querySelectorAll(".button");
  const content = d.querySelectorAll(".menu");
  var toggleClass = "show";

  content.forEach((item) => {
    item.classList.add("hide");
  });

  buttons.forEach((item) => {
    item.addEventListener("click", (event) => {
      if (item.classList.contains("active")) {
        toggleClass = "hide";
      } else {
        toggleClass = "show";
      }
      hideAll();
      toggleDiv(item, item.dataset.destination);
    });
  });

  function hideAll() {
    content.forEach((item) => {
      item.classList.add("hide");
      item.classList.remove("show");
    });
    buttons.forEach((item) => {
      item.classList.remove("active");
    });
  }

  function toggleDiv(targetButton, targetDiv) {
    if (toggleClass === "show") {
      targetButton.classList.add("active");
    }
    d.querySelector("#" + targetDiv).classList.add(toggleClass);
  }
})(document);