<style>
.a{
font-size: 100px;
position: relative;
}
.b{
position: absolute;
color: red;
top: 0;
left: 0;
}
</style>
<span class="a"><span class="b"></span></span> code is shown in the figure above. When the span element of .b is used as a child of span of .an and the child absolute parent phase is applied, there will be a problem with the following picture
.bspanline-height:100px
. Later, I added display:block/inline-block to the span style of the parent element to make the two elements completely overlap. Why? Is there any other solution?