clear float php

Clear float PHP

Float (float) is a very important property in CSS, which can make elements float on the page, making the layout more flexible. However, when we use floats, we often encounter layout problems caused by floated elements. Clearing floats is one of the methods used to solve these problems.

What is clear float?

Clear float is used to solve the problem of the impact of floating elements on page layout. When we use float, the element will float to the specified position on the page. Other elements (especially subsequent elements) may appear to be out of order. At this time, we need to use clear float to solve this problem.

In CSS, clearing floats means using the clear attribute to clear the floating state of the container where the floating element is located, so that the layout returns to the normal state. When using clear, you can use two common methods: the empty element method and the pseudo-element method.

How to clear floats using empty elements

Clearing floats with empty elements is a conventional method of clearing floats. The principle is to add an empty element at the end of the floating element container, then mark the empty element with clearfix, and use CSS to clear the floating element.

The following is a sample code:

.clearfix:after {
    content: "";
    display: block;
    height: 0;
    clear:both;
    visibility: hidden;
}
.clearfix {
    zoom: 1;
}

In this method, we use the pseudo elements: before and: after. Specifically, we add an empty element at the end of the container and mark it with a clearfix tag. Then use CSS to clear the float. Using this method clears floats nicely and does not affect the layout of other elements.

How to use pseudo elements to clear floats

In addition to using empty elements to clear floats, we can also use pseudo elements to clear floats. The principle of this method is to use the :before pseudo-element in the floating element container and clear the floating style.

The following is a sample code:

.clearfix:before,
.clearfix:after {
    content: "";
    display: table;
}
.clearfix:after {
    clear:both;
}

In this method, we use the :before and :after pseudo-elements. Specifically, we use the :before pseudo-element in the container and give it a clear float style. Using this method clears floats nicely and does not require adding additional HTML elements.

Notes

When using clear floats, we need to pay attention to the following points:

1. The method of clearing floats must be placed behind the floating element container, otherwise Clearing the float will have no effect.
2. Cleared floated elements must have a clear height. Otherwise, some strange problems may occur during layout.
3. Using empty elements and using pseudo elements to clear floating elements can effectively solve the impact of floating elements on page layout. However, the method using pseudo-elements is more concise and therefore more popular among developers.

Summary

In CSS, clearing floats is one of the important methods to solve layout problems. When using clear float, we can choose to use empty elements or pseudo elements. Either way, it's a good way to solve layout problems caused by floating elements. When using clear float, you need to pay attention to the position of the clear float, the height of the element, etc.

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