style.css

.draw-border {
  box-shadow: inset 0 0 0 4px #58afd1;
  color: #58afd1;
  transition: color 0.25s 0.0833333333s;
  position: relative;
}
.draw-border::before, .draw-border::after {
  border: 0 solid transparent;
  box-sizing: border-box;
  content: '';
  pointer-events: none;
  position: absolute;
  width: 0;
  height: 0;
  bottom: 0;
  right: 0;
}
.draw-border::before {
  border-bottom-width: 4px;
  border-left-width: 4px;
}
.draw-border::after {
  border-top-width: 4px;
  border-right-width: 4px;
}
.draw-border:hover {
  color: #ffe593;
}
.draw-border:hover::before, .draw-border:hover::after {
  border-color: #ffe593;
  transition: border-color 0s, width 0.25s, height 0.25s;
  width: 100%;
  height: 100%;
}
.draw-border:hover::before {
  transition-delay: 0s, 0s, 0.25s;
}
.draw-border:hover::after {
  transition-delay: 0s, 0.25s, 0s;
}

.btn {
  background: none;
  border: none;
  cursor: pointer;
  line-height: 1.5;
  font: 700 1.2rem 'Roboto Slab', sans-serif;
  padding: 1em 2em;
  letter-spacing: 0.05rem;
}
.btn:focus {
  outline: 2px dotted #55d7dc;
}

body {
  background: #1f1a25;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
}