You used tabs to indent the lines. Tabs are 'funny' in that their indent sticks to a tabstop, at 8 spaces. Adding spaces in front of them doesn't work, up to a point until you add enough.

Add to that that this is browser dependent; Stack Overflow on the other hand interprets tabs as 4 spaces instead.

I replaced all tabs with spaces.

You used tabs to indent the lines. Tabs are 'funny' in that their indent sticks to a tabstop, at 8 spaces. Adding spaces in front of them doesn't work, up to a point until you add enough.

Add to that that this is browser dependent; Stack Overflow on the other hand interprets tabs as 4 spaces instead.

I replaced all tabs with spaces.

However, if you are stuck on IE8 fixed in Compatibility Mode, you are not going to get the full Stack Overflow experience. IE8 is no longer supported by the developers, and Compatibility Mode has never been supported.