Ask the experts, a confusing question. _html/css_WEB-ITnose

Experts, please tell me why the value in in the following code is 1 or 2 to display the gray effect of the mouse on the picture, but when it is set to 3, it cannot be displayed. I I have tried it n times, why is this? I saw a video in which the code was the same as this one, which showed the gray effect when . I was very confused and entangled. why is that?

Reply Discussion (Solution)

Your defined style should have nothing to do with href. Secondly, when using filter, you must consider compatibility issues

Your defined style should have nothing to do with href. Secondly, When using filters, you need to consider compatibility issues
Please tell me, how can it run when I modify a href=1 or 2? Does this have anything to do with filters?

Roots 1, 2, and 3 don’t matter. I tried it in ff and it didn’t change the color when you cross it. The filter needs to consider compatibility, as well as a:link and a:hover
The display effect in different browsers is also different

Thanks to all my friends for finding the problem. The problem has been solved and distributed.