CSS div 100% height

Set the html tag, too. This way no weird position hacks are required.

html, body {height: 100%}

CSS Flexbox was designed to simplify creating these types of layouts.

html {
  height: 100%;
}

body {
  height: 100%;
  display: flex;
}

.Content {
  flex-grow: 1;
}

.Sidebar {
  width: 290px;
  flex-shrink: 0;
}

<div class="Content" style="background:#bed">Content</div>
<div class="Sidebar" style="background:#8cc">Sidebar</div>

Tags:

Css

Height

Css Position

Related