W3Schools Tryit Editor

<!DOCTYPE html>
<html>
<head>
<style>
.button {
  background-color: #04AA6D; /* Green */
  border: none;
  color: white;
  padding: 15px 32px;
  text-align: center;
  text-decoration: none;
  display: inline-block;
  font-size: 16px;
  margin: 4px 2px;
  cursor: pointer;
}

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

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

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

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

.button5 {
  background-color: white;
  color: black;
  border: 2px solid #555555;
}
</style>
</head>
<body>

<h2>Colored Button Borders</h2>

<p>Use the border property to add a border to the button:</p>

<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>

</body>
</html>

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<!DOCTYPE html><html><head><style>.button {  background-color: #04AA6D; /* Green */  border: none;  color: white;  padding: 15px 32px;  text-align: center;  text-decoration: none;  display: inline-block;  font-size: 16px;  margin: 4px 2px;  cursor: pointer;}​.button1 {  background-color: white;   color: black;   border: 2px solid #04AA6D;}​.button2 {  background-color: white;   color: black;   border: 2px solid #008CBA;}​.button3 {  background-color: white;   color: black;   border: 2px solid #f44336;}​.button4 {  background-color: white;  color: black;  border: 2px solid #e7e7e7;}​.button5 {  background-color: white;  color: black;  border: 2px solid #555555;}</style></head><body>​<h2>Colored Button Borders</h2>​<p>Use the border property to add a border to the button:</p>​