<div class="border" id="top">borderで線を引く</div>
<div class="border" id="right">borderで線を引く</div>
<div class="border" id="bottom">borderで線を引く</div>
<div class="border" id="left">borderで線を引く</div>
.border{
    margin-top:15px;
    padding: 10px;
    background: #f2f2f2;
}

#top{
  border-top: 3px solid #333;
}

#right{
  border-right: 3px solid #333;
}

#bottom{
  border-bottom: 3px solid #333;
}

#left{
  border-left: 3px solid #333;
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.