JSFiddle - React, Tailwind, and code Playground

HTML

<span><input type="number" min="0" value="0" step="5" onkeydown="return false"  /></span>

CSS

span {
    position: relative;
    outline: 1px solid #00f;
}

span:after {
    content: "";
    width: 100%;
    height: 100%;
    left: 0;
    top: 0;
    position: absolute;
    outline: 1px solid red;
    width: 91%;
}