CloseTag | الشروحات | CSS | خاصية box-sizing في لغة CSS | CSS Box Sizing

<!DOCTYPE html>
<html>
<head>
<style>
.container
{
  display: grid;
  background-color: #2196F3;
  width:100%;
}

.item
{
  background-color: rgba(255, 255, 255, 0.8);
  border: 2px solid rgba(0, 0, 0, 0.8);
  padding: 20px;
  width:300px;
  height:200px;
}
</style>
</head>
<body>

<div class="container">
  <div class="item">
    This div is 300px width + 2px border+ 20px padding = 312
  </div>
</div>

</body>
</html>