Why does the underline on a link shrink?

Question

PHP

Underline at the top of the link 2px. On the site, it works like this: when hovering, the underline on top is 2px and immediately shrinks to 1px. From below, there is no such problem. Here is an example of code, but apparently it's in the bootstrap. Everything works fine on fiddle.
poke

Answer 1

Be sure to use PHP PDO ( Material 1 , Material 2 )
And, of course, to escape.
UPD:
Or even get rid of unnecessary characters in cases where they are not needed. (For example, when only an integer is written to the base, use intval() );

Answer 2

It is in mysql that the easiest way to make an injection, do not listen to these "smart" who offer it. Mysqli, like PDO, supports prepare statements that filter inputs. Casting to type (intval) is good practice, and there is a mysqli_escape_string function that escapes the query

Answer 3

Here, I did it without transform https://jsfiddle.net/gkapn8L1/1/ and everything works fine. Try to avoid transform whenever possible. There I made the animation not the same as yours, but you get the point.