Playground to execute the code doesnt show code unless you press enter key

[vijay2249]

While learning php from the website learn-php.org
I was going through Code execution area and I am unable to find the pre-written code for each exercises unless I press enter key

I tried opening this website in different browsers like in chrome and brave, the problem seems to present in all the browsers

Here are some screenshots of the issue:

Once the page is reloaded:

After pressing "enter" key

PS: to examine we can see empty line 10 that is new line after pressing "enter" key.