Go to www.teamfortress.com. There's an image at the top of the page showing the 9 different characters. When you mouse over each character they become highlighted, indicating that they can be clicked on to go to their profile page.
And if you very slowly move the mouse cursor from one character to another, you'll find there's a tiny little gap as you cross from one character to the next. A brief moment when both characters become de-highlighted. Like there's a little channel separating the hotspots. This happens everywhere where one character's graphic joins another.
There is one exception: the join between the Scout and the Soldier. If you mouse over and highlight the Scout and slowly scroll over to the Soldier, or vice versa, one highlights and the other simultaneously de-highlights. There is no separating border where both become de-highlighted.
If you mouse over the Scout and move to the Pyro, the gap is there. If you mouse over the Soldier and move to the Engineer, the gap is there. If you mouse over any other character and move to its next-door neighbour, every single time, there is a gap. It's just between the Scout and Soldier where there is no gap. It is impossible to position your mouse between them without highlighting either.