Untitled

dabblet.css

.hd, .ft {
  height: 20px;
  background-color: red;
}
.bd {
  overflow: hidden;
}
.bd::after {
  content: '';
  clear: both;
  height: 0;
  line-height: 0;
  visibility: hidden;
  display: block;
}
.main-bar, .side-bar {
  float: left;
  margin-bottom: -99999px;
  padding-bottom: 99999px;
}
.main-bar {
  width: 70%;
  margin-right: 30%;
  background-color: blue;
}
.side-bar {
  width: 30%;
  margin-left: -30%;
  background-color: green;
}

dabblet.html

<div class="hd">hd</div>
<div class="bd">
  <div class="main-bar">
  	main-bar<br>
  	main-bar<br>
  	main-bar<br>
  	main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>main-bar<br>
  </div>
  <div class="side-bar">side-bar</div>
</div>
<div class="ft">ft</div>

dabblet.js

// alert('Hello world!');

settings.json

{"view":"split-vertical","fontsize":"100","seethrough":"","prefixfree":"1","page":"html"}