W3Schools Tryit Editor

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
body {
  font-family: Arial
}

* {
  box-sizing: border-box;
}

/* The browser window */
.container {
  border: 3px solid #f1f1f1;
  border-top-left-radius: 4px;
  border-top-right-radius: 4px;
}

/* Container for columns and the top "toolbar" */
.row {
  padding: 10px;
  background: #f1f1f1;
  border-top-left-radius: 4px;
  border-top-right-radius: 4px;
}

/* Create three unequal columns that floats next to each other */
.column {
  float: left;
}

.left {
  width: 15%;
}

.right {
  width: 10%;
}

.middle {
  width: 75%;
}

/* Clear floats after the columns */
.row:after {
  content: "";
  display: table;
  clear: both;
}

/* Three dots */
.dot {
  margin-top: 4px;
  height: 12px;
  width: 12px;
  background-color: #bbb;
  border-radius: 50%;
  display: inline-block;
}

/* Style the input field */
input[type=text] {
  width: 100%;
  border-radius: 3px;
  border: none;
  background-color: white;
  margin-top: -8px;
  height: 25px;
  color: #666;
  padding: 5px;
}

/* Three bars (hamburger menu) */
.bar {
  width: 17px;
  height: 3px;
  background-color: #aaa;
  margin: 3px 0;
  display: block;
}

/* Page content */
.content {
  padding: 10px;
}
</style>
</head>
<body>

<div class="content">
    <h3>Browser Window</h3>
    <p>How to create a detailed browser window look with CSS.</p>
  </div>
</div>

</body>

</html>

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<!DOCTYPE html><html><head><meta name="viewport" content="width=device-width, initial-scale=1"><style>body {  font-family: Arial}​* {  box-sizing: border-box;}​/* The browser window */.container {  border: 3px solid #f1f1f1;  border-top-left-radius: 4px;  border-top-right-radius: 4px;}​/* Container for columns and the top "toolbar" */.row {  padding: 10px;  background: #f1f1f1;  border-top-left-radius: 4px;  border-top-right-radius: 4px;}​/* Create three unequal columns that floats next to each other */.column {  float: left;}​.left {  width: 15%;}​.right {  width: 10%;}​.middle {  width: 75%;}​/* Clear floats after the columns */.row:after {