JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    <button><span>span</span></button>
</div>

CSS

button::-moz-focus-inner, 
input[type="button"]::-moz-focus-inner, 
input[type="submit"]::-moz-focus-inner, 
input[type="reset"]::-moz-focus-inner {
  padding: 0 !important;
  border: 0 none !important;
}

div {
    height: 300px;
    width: 300px;
    background-color: red;
}
button {
    padding: 0px;
    margin: 0px;
    color: inherit;
    border: 0;
    background-color: blue;
}
span {
    background-color: yellow;
    display: block;
    width: 100%;
}