What is the css box model?

The CSS box model is a thinking model used by CSS technology that is often used in web design. It is also called the Box Model, which is composed of several elements: element content (content), padding (padding), border (border), and outer margin (margin) (as shown in the figure below).

We can understand these attributes by transferring them to the boxes (boxes) in our daily life. The boxes we see in our daily life are also a kind of box that can hold things. They also have these attributes, so they are called It's box mode.

The innermost box in the picture is the actual content of the element, that is, the element box. Next to the outside of the element box is the inner margin padding, followed by The border (border), and then the outermost layer is the margin (margin), which constitutes the box model. Usually the background display area we set is the range of content, padding, and borders. The outer margin is transparent and will not block other surrounding elements.

Then, the total width of the element box = the width of the element (element), the value of the left and right margins of the padding, the value of the left and right margins of the margin, the left and right width of the border;

Element The total height of the box = the value of the top and bottom margins of the height padding of the element, the value of the top and bottom margins of the margin + the top and bottom width of the border.

Structure

Content (CONTENT) is what is in the box;

and padding (PADDING) is afraid of what is in the box (valuable () foam or other anti-seismic accessories added due to damage;

The border (BORDER) is the box itself; as for the border (MARGIN), it means that when the boxes are placed, they cannot all be piled together, and a certain amount of space must be left. Gaps maintain ventilation but also allow for easy removal. In web design, content often refers to text, pictures and other elements, but it can also be small boxes (DIV nested). Unlike boxes in real life, things in real life generally cannot be larger than boxes, otherwise the box will be stretched Broken, and the CSS box is elastic. The things inside are larger than the box itself and will stretch it at most, but it will not be damaged.

Padding has only width attribute, each HTML tag can be regarded as a box;

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