W3Schools Tryit Editor

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
.btn {
  border: 2px solid black;
  background-color: white;
  color: black;
  padding: 14px 28px;
  font-size: 16px;
  cursor: pointer;
}

/* Green */
.success {
  border-color: #04AA6D;
  color: green;
}

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

/* Blue */
.info {
  border-color: #2196F3;
  color: dodgerblue;
}

.info:hover {
  background: #2196F3;
  color: white;
}

/* Orange */
.warning {
  border-color: #ff9800;
  color: orange;
}

.warning:hover {
  background: #ff9800;
  color: white;
}

/* Red */
.danger {
  border-color: #f44336;
  color: red;
}

.danger:hover {
  background: #f44336;
  color: white;
}

/* Gray */
.default {
  border-color: #e7e7e7;
  color: black;
}

.default:hover {
  background: #e7e7e7;
}
</style>
</head>
<body>

<h1>Outline Buttons</h1>

<button class="btn success">Success</button>
<button class="btn info">Info</button>
<button class="btn warning">Warning</button>
<button class="btn danger">Danger</button>
<button class="btn default">Default</button>

</body>
</html>

​x
 
<!DOCTYPE html><html><head><meta name="viewport" content="width=device-width, initial-scale=1"><style>.btn {  border: 2px solid black;  background-color: white;  color: black;  padding: 14px 28px;  font-size: 16px;  cursor: pointer;}​/* Green */.success {  border-color: #04AA6D;  color: green;}​.success:hover {  background-color: #04AA6D;  color: white;}​/* Blue */.info {  border-color: #2196F3;  color: dodgerblue;}​.info:hover {  background: #2196F3;  color: white;}​/* Orange */.warning {  border-color: #ff9800;  color: orange;}​.warning:hover {  background: #ff9800;  color: white;}​