JSFiddle - React, Tailwind, and code Playground

HTML

<button>Новый расчет</button>

CSS

* {
    padding: 0;
    margin: 0;
}
button {
    text-transform: uppercase;
    padding: 0.5em;
    width: 11em;
    border: 1px solid #639828;
    background: linear-gradient(to bottom, #a9c04d 0%, #639828 100%);
    color: white;
    text-shadow: 0 -1px 0 black;
    box-shadow: inset 0 1px 0 #d5e0a6;
    padding-left: 1.5em;
    font-size: 1em;
    position: absolute;
}
button:before {
    content: "";
    position: absolute;
    top: -1px;
    left: -1px;
    height: 0;
    width: 0;
    border-top: calc(1em + 4px) solid white;
    border-right: calc(1em + 4px) solid transparent;
    z-index: 100;
}
button:after {
    content: "";
    position: absolute;
    top: calc(1em + -1px);
    left: -1px;
    height: 0;
    width: 0;
    border-bottom: calc(1em + 4px) solid white;
    border-right: calc(1em + 4px) solid transparent;
    z-index: 100;
}