In CSS section, the answer says "A BFC is an HTML box that satisfies at least one of the following conditions: ... The value of display is table-cell, table-caption, inline-block, flex, or inline-flex."
display flex create a new flex formatting context, not block formatting context. Only flex items (its children) create new BFC.
In CSS section, the answer says "A BFC is an HTML box that satisfies at least one of the following conditions: ... The value of display is table-cell, table-caption, inline-block, flex, or inline-flex."
display flex create a new flex formatting context, not block formatting context. Only flex items (its children) create new BFC.