当您删除
display属性时，它确实起作用。
#myelem { opacity: 0; transition: opacity 0.4s ease-in; -ms-transition: opacity 0.4s ease-in; -moz-transition: opacity 0.4s ease-in; -webkit-transition: opacity 0.4s ease-in;}#myelem.show { opacity: 1; transition: opacity 0.4s ease-out; -ms-transition: opacity 0.4s ease-out; -moz-transition: opacity 0.4s ease-out; -webkit-transition: opacity 0.4s ease-out;}原因是只能转换带有数字的CSS属性。您认为“ 50％状态”应介于“
display: none;”和“
display:block;”之间是什么？由于无法计算该值，因此无法为该
display属性设置动画。
