Check out example codes for "button style none". It will help you in understanding the concepts better.

Code Example 1

button, input[type="submit"], input[type="reset"] {
	background: none;
	color: inherit;
	border: none;
	padding: 0;
	font: inherit;
	cursor: pointer;
	outline: inherit;
}

Code Example 2

button {
  background: transparent;
  box-shadow: 0px 0px 0px transparent;
  border: 0px solid transparent;
  text-shadow: 0px 0px 0px transparent;
}

button:hover {
  background: transparent;
  box-shadow: 0px 0px 0px transparent;
  border: 0px solid transparent;
  text-shadow: 0px 0px 0px transparent;
}

button:active {
  outline: none;
  border: none;
}

button:focus {
  outline: 0;
}

Code Example 3

button {
    border: none;
}

button:focus {
    border: none;
    outline: none;
}

button:focus{
    outline:none !important;
}
(add !important if it is used in Bootstrap)

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