<button>BUTTON</button>

/* vars */

button {
  --border-width: 2px;
  --border-radius: 22px;
  --color-1: #f19f39;
  --color-2: #de222c;
}

/* code */

button {
  font-weight: bold;
  letter-spacing: 1px;
  color: #ddd;
  width: 120px;
  position: relative;
  background: linear-gradient(to right, orange, red),
    linear-gradient(to right, orange, red);
  background-position: var(--border-radius) 0, var(--border-radius) 100%;
  background-repeat: no-repeat;
  background-size: calc(100% - var(--border-radius) - var(--border-radius))
    var(--border-width);
  padding: 14px 24px;
  border-radius: var(--border-radius);
  border: none;
}

button:before,
button:after {
  content: "";
  display: block;
  position: absolute;
  width: var(--border-radius);
  top: 0;
  bottom: 0;
}

button:before {
  left: 0;
  border: var(--border-width) solid var(--color-1);
  border-top-left-radius: var(--border-radius);
  border-bottom-left-radius: var(--border-radius);
  border-right-color: transparent;
}

button:after {
  right: 0;
  border: var(--border-width) solid var(--color-2);
  border-top-right-radius: var(--border-radius);
  border-bottom-right-radius: var(--border-radius);
  border-left-color: transparent;
}

/* bg */

body,
html {
  background: #2b2d42;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100%;
}