Many web pages use box model to organize the web content. For example, when I inspect MDN homepage, I see there are box shapes on the page. Some boxes are visible, but some boxes are invisible.
No matter those boxes are visible or invisible, the main purpose to use box model is to let the web page have an appropriate layout, which allow users to catch the clear information and easy to read.
What Is The Box Model?
According to MDN, in a document, each element is represented as a rectangular box. In CSS, each of these rectangular boxes is described using the standard box model.
Each box has four edges: margin, border, padding and content edge.
from MDNContent:The content of a CSS box is where the text and images appear. The“width” and “height”properties set the width and height of content box.
Padding: Padding refers to the inner margin of a CSS, and it is transparent. The properties include padding-top, padding-right, padding-bottom, and padding-left.
Border:The border of a CSS box goes around the padding and content. The properties include border-top, border-right, border-bottom, and border-left. And we can also set the border width, style, and color.
Margin: The margin surrounds a CSS box, and it is outside the border. It is also transparent. The properties includes:margin-top, margin-left, margin-bottom, and margin-right. (Above Definition are From MDN Box Model)
Now I am going to show an example to explain each element of CSS box.
I create a simple HTML page includes two “headers” and one “content”. Each content has a border around it.
In order to let you see how the box change, I will only make the red content box change.
I begin from the outside CSS box to inside box. Firstly, I set the outside box margin 50px. You can see the space between two black box and red box are getting bigger.
Secondly, I set the padding, the inside margin, as 50px, too. The inside margin is larger than the previous one.
If you want to move the “content” to the center, you can also try to set the padding-left properties.
Thirdly, I set the border. I only change the border-bottom to “10px dashed blue” style, so you can see the difference between the red and blue border.
Lastly, I set the content width and height in 200px, then the red box become a square.
You can always inspect (right click the web page and select the inspect) the page and change the property value and see the differences.