CSS web page layout misalignment: CSS width calculation

Why Calculate Width
Calculating the pixel width of web pages is for the sake of CSSweb page layout 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 and margin layout. If we do not calculate the width, 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:

Left 300px

Right 100px

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, then the total width exceeds 20px. Let’s see what problems will occur. The DIV+CSS code is as follows:

Left 300px

Right 100px

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, when the difference is small, it is usually 1px-2px, which will not be discovered by us. Therefore, to eliminate misalignment compatibility, we can start with width calculation.

Example 2: There is an example of 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 calculate the width of the border and the width of the left and right structures together.
Correct example:
CSS and html code are as follows:

< ;div class="webjxcom">

Left 300px

Right 100px

Since both the left and right structures have a width of 1px, you need to subtract the left and right border widths of 2 pixels each, so the left side ends up with a width of 298px, and the right side has a width of 98px

If the border is not subtracted, the following effects will occur:

DIV+CSSSet percentage width calculation
Sometimes we also need to use percentage to calculate 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 DIV width layout setting, you need to pay attention to the grasp and calculation of the width, especially when using padding, margin, border, etc. CSS attributes At this time, we all need to calculate the occupied widths 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, misalignment compatibility problems will occur. So 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.