【CSS深入】不同块级流方向时的百分比计算_html/css_WEB-ITnose

Note that in a horizontal flow, percentages on ‘margin-top’ and ‘margin-bottom’ are relative to the width of the containing block, not the height (and in vertical flow, ‘margin-left’ and ‘margin-right’ are relative to the height, not the width).[1]

Note that percentages on ‘padding-top’ and ‘padding-bottom’ are relative to the width of the containing block, not the height (at least in a horizontal flow; in a vertical flow they are relative to the height).[2]

水平流？垂直流？那是什么鬼？