I have created a button and every time I long press it or click on it, a square blue fill is showing, I tried removing it with outline: 0 and -webkit-tap-highlight-color: transparent;, but it didn't work. Here is my code :-

.mybutton:focus {
    outline: none;
    -webkit-tap-highlight-color: transparent;
    background: rgba(0, 0, 0, 0.40);
}```