Simple Box is a free Tumblr theme that features a minimal and clean design. This theme has been made using lines and boxes where you can insert your texts and other content beautifully. This theme is fully responsive as well, which helps you to display your blog elegantly over any device. Not to mention, this theme is cross-browser compatible and retina ready. If you are looking for a simple theme to display your content without much complexity, this theme will serve your purpose. With this theme, you can also create your custom pages and display navigation to them over the sidebar menu.