div css implements prompt box with triangular arrow_html/css_WEB-ITnose

The prompt box with a triangular arrow is as shown below:

This is a prompt box

Usually we use pictures to realize the small triangle above because it is convenient and fast. However, if the picture is not processed well, it will look cluttered and affect the vision, so we need to use another way of thinking to solve it.

First, let’s study how CSS implements triangles.

Assume there is a box (div), with a given width and height of 100 pixels, and a border of 50 pixels, then it will look like the following (in order to be more intuitive, four different borders are given color):

Next, set the height of the box to 0:

Then set the width to 0:

The prototype will be It has been released. Due to the bug of IE6 (a div with a height of 0 will have a certain default height, the measurement result on my computer is 19 pixels), some small adjustments need to be made. Add an overflow:hidden to the div, and IE6 will be able to correct it. Parsed.

The next step is to remove the remaining three borders. Take the upward arrow as an example. If I want the arrow to point upward, then I need to remove the colors of the left, upper, and right borders. A common method is to set the color of these three borders to transparent, that is, the transparent attribute.

border-color:transparent transparent #056F61

After setting, you can see the following effect:

In this way, the triangle created by CSS is completed. At this point, it seems that the work is almost over. We still need to test the compatibility of the browser. After testing, all mainstream browsers support it. However, when I open IE6, the result is sad. It looks like this (T-T):

I checked where the problem was and found out that IE6 does not support the transparent attribute. What should I do? So much work has been done in the past, we can't let it fall under IE6.

So I checked on the Internet how to support transparent in IE6, and it turns out that I need to use filters. However, this solution will definitely not work. If you want to use filters, it is better to use pictures directly. After some further research,

found that it would be ok if the attributes of the remaining three edges were changed from solid to dotted or dashed:

/*border-style:solid*/border-style:dotted dotted solid;border-width:50px;border-color:transparent transparent #056f61; 

This looks like IE6 It "supports" the transparent attribute. Why is this happening? I haven't figured this out yet. After testing, it was found that if the border type of the box is set to dashed, there will be a strange behavior under IE6:

When the width and height of the box are 100 pixels, the width of the border is 34 pixels and the type is dashed , the border will disappear, and will be displayed again when it is set to 33 pixels, and this ratio is certain.

This may explain why IE6 displays "normal" when changing the border type to dashed.

When the border type is dotted, IE6 displays as follows:

The black dot disappears when the width and height of the box are set to 0, and IE6 also displays "normal" at this time .

Although there may be problems with IE6's parsing, it has finally "solved" the bug of not supporting transparent.

The next step is very simple. Make a triangle with the same background as the prompt box, superimpose it on the previous triangle, leaving only one pixel on the side, and then position it on the prompt box.

You can make the left, right and bottom triangles according to your needs.

The above are some personal experiences. Please correct me if there are any mistakes.

Source code: Prompt box with triangular arrow

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