Hi, the 100% XP bonus is for any class below lvl 60 below your highest level class ^^

So for example if you got a lvl 20 Gladiator any class below lvl 20 will get the bonus until they're equal to that level, then if you for example level your conjurer to 30 your gladiator will get 100% bonus until it reaches that too. and that continues till 60

After level 60 you only get 50% for any class below your highest level