If you have many blog posts that contain the preformatted text you can add the following code in Custom CSS. You get the same aspect as the code below.
{ border-style: dotted; border-width: 2px; border-color: #aaaaaa; background-color: #f2f2f2; padding: 10px; font-family: 'Roboto Mono', monospace; font-size: 15px; word-break: break-word; white-space: pre-wrap; }
Photo by Teng Yuhong on Unsplash