<!doctype html>
<meta charset="utf-8">
<title>Big button with gradient (without padding)</title>
<style>
    #button {
        width: calc(300px + 2 * 30px);
        height: calc(80px + 2 * 20px);
        background: linear-gradient(blue, green);
        border-width: 5px;
        border-style: solid;
        border-color: red;
        border-radius: 10px;
    }
</style>
<div id="button"></div>