CSS uses :before :after to write small triangle examples to share-CSS Tutorial-php.cn

This article mainly introduces the detailed information on how to use :before :after to write small triangles in CSS. The editor thinks it is quite good, so I will share it with you now and give it as a reference. Let’s follow the editor to take a look, I hope it can help everyone.

The triangles written before are always in the same color and have no border style. As follows:

The CSS code is as follows:

.tri-up{width: 0;height:0;border-left:20px solid transparent;border-right: 20px solid transparent;border-bottom: 20px solid red; } .tri-left{width: 0;height:0;border-top:20px solid transparent;border-bottom: 20px solid transparent;border-left: 20px solid red;} .tri-right{width: 0;height:0;border-top:20px solid transparent;border-bottom: 20px solid transparent;border-right: 20px solid red;} .tri-down{width: 0;height:0;border-left:20px solid transparent;border-right: 20px solid transparent;border-top: 20px solid red; }

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To write the following small triangle, you need to use pseudo Class:before :after

CSS code:

#demo { margin: 100px;; width: 100px; height: 100px; background-color: #fff; position: relative; border: 2px solid #333; } //方框的样式 #demo:after, #demo:before { border: solid transparent; content: ' '; height: 0; left: 100%; //根据三角形的位置，可以随意更改。 position: absolute; width: 0; } #demo:after { border-width: 10px; border-left-color: #fff; top: 20px;//根据三角的位置改变 }//此处是一个白色的三角 #demo:before { border-width: 12px; border-left-color: #000; top: 18px; }此处是一个黑色的三角 //当#demo:after和#demo:before的样式重合以后，由于top值的大小不同，就可以得到中间是白色，但是边框的三角形。如上图。

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If To change to the style of the picture below:

The CSS code is as follows:

#demo { margin: 100px;; width: 100px; height: 100px; background-color: #fff; position: relative; border: 2px solid #333; } #demo:after, #demo:before { border: solid transparent; content: ' '; height: 0; top: 100%; position: absolute; width: 0; } #demo:after { border-width: 10px; border-top-color: #fff; left: 20px; } #demo:before { border-width: 12px; border-top-color: #000; left: 18px; }

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