Visibility of multi-column attribute column elements: display, visibility, opacity, vertical alignment: vertical-align, z-index The larger it is, the more it will be displayed on the upper layer

div (page division) span (use style within one line)

width attribute: set the width of the content display area ----- only valid for block elements (h1, p,) and img elements

Multi-column attributes

column-count: specifies the number of columns that the element should be divided into - an integer ;
column-gap: specifies the interval between columns - px pt em % ;
column-rule: sets the number of columnsVertical bar width, style and color rules between 2px solid green ;
column-span: specify how many columns the element should span - 1 all;
column-width: specify the width of the column - px pt em%;

Center horizontally: margin

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Vertical alignment: vertical-align:

baseline (default, the element is placed on the baseline of the parent element) top (the top of the element is aligned with the top of the tallest element in the row) middle (the element is placed in the middle of the parent element) bottom (the top of the element is aligned with the top of the rowtop of the element that is the lowest inbottom-aligned parent element font)

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Element visibility: the higher the z-index, the more visible

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Element visibility: display

display: Set the type of box that the element should generate - block (setting the element to a block element can convert a row element into a block element and then set the width, with line breaks before and after the element) inline (default value, the element is displayed as an inline element, which can be displayed on one line without line breaks before and after the element)none (the element will not be realistic, the element will not occupy space on the page);
visibility: set whether the element is visible - visible (default value)The element is visible) hidden (the element is invisible, the element still occupies the page space);
opacity: set the transparency of the element - 0.0 completely transparent -> 1.0 completelyOpaque;