button { --border-radius: 15px; --border-width: 4px; appearance: none; position: relative; padding: 1em 2em; border: 0; background-color: #212121; font-family: "Roboto", Arial, "Segoe UI", sans-serif; font-size: 18px; font-weight: 500; color: #fff; z-index: 2; } button::after { --m-i: linear-gradient(#000, #000); --m-o: content-box, padding-box; content: ""; position: absolute; left: 0; top: 0; wi