sqlfiddle: leading blanks are gone
Response from admin@sqlfiddle.com (originally provided by miracle173 in a comment):

If you change the output format to &quot;plaintext&quot; rather than &quot;tabular&quot; (the default) you'll see the whitespace there like you expect. You can change the format by clicking the down arrow next to &quot;Run SQL&quot;.
The reason you aren't seeing it in tabular mode is because by default html ignores more than one whitespace character, and I'm not bothering to do any work to override this default behavior for tabular formatting.