I created a CodePen to compare it with jsfiddle. I added the html and the css. But...what now? How do I get it to show the results?In jsfiddle you select Run and, when satisfied, Update. But what's the trick in codePen? I'm sure it's obvious, but I searched all over to no avail.The white presentation page is visible at the bottom; PenSettings are set to AutoSave and Auto Update Preview.The same HTML and CSS renders fine at this jsfiddle
How do you get CodePen to display the results?
html;css
The results should appear instantly (by default) in the preview window at the bottom. By default, in Pen Settings, the option Auto Update Preview is checked (the preview will update automatically when you change code). If this is unchecked then you get a Run button in the toolbar.However, it appears that you have reached a limitation of CodePen! This blog post discusses file size limitations and states that:One of the limitations of the CodePen editor is sheer volume of code. ... when they start hitting 5,000 - 10,000 or more lines of code, you'll see the editor start to fail.In your example, you had 13,000+ lines of HTML and indeed it failed to Preview, even with the Auto Update Preview option unchecked and hitting Run manually. However, chopping the code down to about 5,000 lines produced a result. (It would have been useful to have had some kind of advisory/warning, since nothing is not particularly helpful!)