El-steps component height collapse in IE11

The reason why the el-step component collapses in IE11 is caused by the flex layout.
Wrap a layer of container outside the el-step component, and set disp:flex
to add the property flex-grow:1 to the el-step component; at the same time, set a min-height
to solve the problem
. Later, the step node also encountered a collapse problem, because flex:1 is not supported in IE Under
standard browsers: flex: 1 1 auto; under
IE: flex: 1 1 0;
compatible method: => flex:1 1 auto;
or set the property: flex-basis:auto;