Detailed explanation of CSS web page layout misalignment width calculation instructions-CSS Tutorial-php.cn

Detailed explanation of CSS web page layout misalignment width calculation instructions

高洛峰

Release： 2017-03-17 14:20:35

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Why calculate the width
Calculating the pixel width of the web page is to CSSThe web page layout is neat and compatible. It is common for us to calculate the width of the entire page when we lay out the left and right structural web pages or use padding, margin layout. If we do not calculate the width, no matter whether the width is too large or too small, misalignment problems will occur.

How to calculate CSS width
Example 1: We calculate the layout style of a left and right structure.
If the total width is 400px, then the sum of the left and right should be less than 400px, then we may have 300px on the left and 100px on the right
Correct code:

<head>

< p class="zuo">300px on the left

100px on the right

The above is the correct total width of the left and right structures, which is exactly equal to 400px

Error:
If we keep the total width unchanged, the left side is 300px, and The right side is 120px, so the total width exceeds 20px. Let’s see what problems will occur. The p+CSS code is as follows:

Calculation of left and right structure width www.webjx.com

< p class="zuo">300px on the left

100px on the right

We can see from the picture above that because the total width is about 20px, the left and right structures cannot be flush, and the right side falls down.
In this way, misalignment compatibility issues arise. Generally, in practice, due to our negligence in calculation, the difference is usually 1px-2px when the difference is small, which will not be discovered by us. Therefore, to eliminate misalignment compatibility, we can start with width calculation.

Example 2: There is a 1px border in the left and right structure
Generally, there is a 1px border in the left and right structure, and then some borders are added. When we set the left and right structures, we need to match the border width with the width of the left and right structures. calculated together.
Correct example:
CSS and html code is as follows:

< ;meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
Calculation of left and right structure width www.webjx.com

300px on the left

100px on the right

Because the left and right structures have a width of 1px, you need to subtract the left and right 2 pixel borders each. Width, so the width on the left is 298px and on the right is 98px

If the border is not subtracted, the following effect will be caused:

p+CSSSet percentage width calculation
Sometimes we also need to use percentage to calculate the width. Usually it is also the total percentage width, which cannot exceed 100%

Pay attention to summary when calculating CSS width:
Whether it is a left-right structure, a multi-column layout, or a single p-width layout setting, you need to pay attention to the grasp and calculation of the width, especially when using padding, margin, borders, etc.CSS properties, at this time we all need to calculate the occupied width they set, and firmly grasp that the sum of the widths of the same row is less than or equal to the total width, if it is greater than the total width, it will appear Misplaced compatibility issues. Therefore, when there is general misalignment, we can start by calculating the width. Of course, there are many reasons for misalignment. This is also one of the methods to solve the misalignment compatibility problem.

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