<!DOCTYPE html>
<html lang="en">
<head>
<title>Responsive </title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.6.3/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/js/bootstrap.min.js"></script>
<style>
.b {border: solid 2px orange;}
</style>
</head>
<body>
Visible-md: md모드일때 보이기
<div class="container-fluid">
<div class="row">
<div class="col-md-3 b">JAVA</div>
<div class="col-md-6 b visible-md">CSS</div>
<div class="col-md-3 b">HTML</div>
</div>
</div>
hidden-mode: md모드일때 숨기기
<div class="container-fluid">
<div class="row hidden-md">
<div class="col-md-3 b">JAVA</div>
<div class="col-md-6 b">CSS</div>
<div class="col-md-3 b">HTML</div>
</div>
</div>
Offset: 빈 여백으로 남김
<div class="container-fluid">
<div class="row">
<div class="col-md-4 col-md-offset-4 b">JAVA</div>
<div class="col-md-4 b">CSS</div>
</div>
</div>
row안에 row 가능
<div class="container-fluid">
<div class="row">
<div class="col-md-3 b">KO</div>
<div class="col-md-6 b">
<div class="row">
<div class=" col-md-4 b">HTML</div>
<div class=" col-md-4 b">CSS</div>
<div class=" col-md-4 b">JAVA</div>
</div>
</div>
<div class="col-md-3 b">CH</div>
</div>
</div>
</body>
</html>
