Formal description found online:
Reference content
This value causes an element to generate a block box model (block box), and itself flows as a single inline box model (inline box), similar to A replaced element. The element whose Display value is inline-block forms a block box model internally, and itself forms like an inline replaced element
PS: Unfortunately, IE does not support it, and FF does not support it either. HOHO~
IE solution: Trigger IE's layout so that the element has line-block-like characteristics.
FF solution: use moz-specific attributes: display::-moz-inline-box;