Style.css dosyalarına veya engine.css dosyalarına aşağıdaki kodu yapıştırıp kayıt ediniz.

.button {
  background-color: #04AA6D; /* Green */
  border: none;
  color: white;
  padding: 16px 32px;
  text-align: center;
  text-decoration: none;
  display: inline-block;
  font-size: 16px;
  margin: 4px 2px;
  transition-duration: 0.4s;
  cursor: pointer;
}

.button1 {
  background-color: white; 
  color: black; 
  border: 2px solid #04AA6D;
}

.button1:hover {
  background-color: #04AA6D;
  color: white;
}

.button2 {
  background-color: white; 
  color: black; 
  border: 2px solid #008CBA;
}

.button2:hover {
  background-color: #008CBA;
  color: white;
}

.button3 {
  background-color: white; 
  color: black; 
  border: 2px solid #f44336;
}

.button3:hover {
  background-color: #f44336;
  color: white;
}

.button4 {
  background-color: white;
  color: black;
  border: 2px solid #e7e7e7;
}

.button4:hover {background-color: #e7e7e7;}

.button5 {
  background-color: white;
  color: black;
  border: 2px solid #555555;
}

.button5:hover {
  background-color: #555555;
  color: white;
}

<button class="button button1">Green</button>
<button class="button button2">Blue</button>
<button class="button button3">Red</button>
<button class="button button4">Gray</button>
<button class="button button5">Black</button>

Yazarak kontrol edebilirsiniz.