.placeholder-box {
  position: relative;
  display: block;
  width: 300px;
  min-height: 150px;
  margin-top: 50px;
  padding: 30px;
  border: 1px solid #888;
  border-radius: 10px;
  box-sizing: border-box;
  box-shadow: 0 0 8px 0 rgba(0,0,0,0.25);
}

.placeholder-box p {
  text-align: center;
  margin: 0 0 15px;
}

.placeholder-box ul {
  margin: 0;
}

/* Button */

button {
 display: block;
 border: solid white;
 border-width: 0 10px;
 border-radius: 0;
 background: green;
 color: white;
 font-size: 18px;
 margin: -60px auto 15px;
 padding: 15px;
}

<div class="placeholder-box">
  <button type="button"> Button Text Here </button>
  <p>Nunc condimentum mauris elit</p>
  <ul>
    <li>Duis quis eros felis</li>
    <li>Nulla facilisi</li>
  </ul>
</div>

<div class="pure-button-group" role="group" aria-label="...">
    <button class="pure-button">A Pure Button</button>
    <button class="pure-button">A Pure Button</button>
    <button class="pure-button pure-button-active">A Pure Button</button>
</div>

.button {
  background-color: #4CAF50; /* Green */
  border: none;
  color: white;
  padding: 15px 32px;
  text-align: center;
  text-decoration: none;
  display: inline-block;
  font-size: 16px;
}

<a rel="nofollow" class="pure-button pure-button-primary" href="#">A Primary Button</a>
<button class="pure-button pure-button-primary">A Primary Button</button>