What is the box model in css?

The CSS box model is a thinking model used by CSS technology that is often used in web design.

css box model is also called the box model (Box Model). It contains several elements such as element content (content), inner margin (padding), border (border), and outer margin (margin) to form a box. Model. As shown in the picture:

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.

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.

Features

Imagine a box, which has four attributes: margin, border, padding, and content;

Let's look down at this box. It has four sides, top, bottom, left, and right, so each attribute includes four parts in addition to content: top, bottom, left, and right; these four parts can be set at the same time or separately; the padding can It is understood as the distance between the content in the box and the border, and the border is divided into thickness and color. The content is the content in the middle of the box, and the margin is the blank space automatically left outside the border.

Structure editing

Content (CONTENT) is what is in the box;

and padding (PADDING) is added for fear that the things in the box (valuable) will be damaged. foam or other earthquake-resistant auxiliary materials;

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 gap must be left to maintain ventilation. Also 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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