Yes,
When I quoted your post (with the quotes inside it), there were a couple of errors (which I corrected, so you can see the correct effect in my post) where you had tried to create a quote.
A quote on its own without any content just draws a very thin box, which looks like a thick line. One of the quotes began with a double square bracket ( [ [ , I had to amend this (add a space) as only one [ was displayed, meaning it is looking for a closing ] after the first one) and this I believe caused the major problem with the formatting. It would appear that you tried to add a quote within a quote.
I have to exercise care with my browser (firefox), which has a serious flaw in its posting within forum boards. I have to install an extension to handle forum posts. I can't use the buttons above the text window as firefox doesn't place them at the cursor point but at the bottom/end of the text. So your browser could have an effect.