Difference between inline box and atomic inline box

Question

Consider the following code:

div{
    display: inline-block;
}

div block is generated atomic inline-level box now. As

Answer 1

Indeed. Referring to Visual Formatting Model

Some emphasized text

anonymous inline boxes inherit inheritable properties from their block parent box. Non-inherited properties have their initial value. In the example, the color of the anonymous inline boxes is inherited from the P, but the background is transparent