HTMLify

body {
    display: grid;
    place-items: center;
    height: 100vh;
    background: #222;
  }
  
  .button {
    --offset: 10px;
    --border-size: 2px;
    display: block;
    position: relative;
    padding: 1.5em 3em;
    -webkit-appearance: none;
       -moz-appearance: none;
            appearance: none;
    border: 0;
    background: transparent;
    color: #e55743;
    text-transform: uppercase;
    letter-spacing: 0.25em;
    outline: none;
    cursor: pointer;
    font-weight: 700;
    border-radius: 0;
    box-shadow: inset 0 0 0 var(--border-size) currentcolor;
  }
  
  .button:hover {
    background: rgba(100, 0, 0, 0.03);
  }
  
  .button__horizontal, .button__vertical {
    position: absolute;
    top: var(--horizontal-offset, 0);
    right: var(--vertical-offset, 0);
    bottom: var(--horizontal-offset, 0);
    left: var(--vertical-offset, 0);
    transition: transform 0.8s ease;
    will-change: transform;
  }
  
  .button__horizontal::before, .button__vertical::before {
    content: "";
    position: absolute;
    border: inherit;
  }
  
  .button__horizontal {
    --vertical-offset: calc(var(--offset) * -1);
    border-top: var(--border-size) solid currentcolor;
    border-bottom: var(--border-size) solid currentcolor;
  }
  
  .button__horizontal::before {
    top: calc(var(--vertical-offset) - var(--border-size));
    bottom: calc(var(--vertical-offset) - var(--border-size));
    left: calc(var(--vertical-offset) * -1);
    right: calc(var(--vertical-offset) * -1);
  }
  
  .button:hover .button__horizontal {
    transform: scaleX(0);
  }
  
  .button__vertical {
    --horizontal-offset: calc(var(--offset) * -1);
    border-left: var(--border-size) solid currentcolor;
    border-right: var(--border-size) solid currentcolor;
  }
  
  .button__vertical::before {
    top: calc(var(--horizontal-offset) * -1);
    bottom: calc(var(--horizontal-offset) * -1);
    left: calc(var(--horizontal-offset) - var(--border-size));
    right: calc(var(--horizontal-offset) - var(--border-size));
  }
  
  .button:hover .button__vertical {
    transform: scaleY(0);
  }