<button>Neumorphism</button>

body {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  margin: 0;
  background: #efefef;
}
button {
  padding: 1.5em 5em;
  background: #efefef;
  border: none;
  border-radius: .5rem;
  color: #444;
  font-size: 1rem;
  font-weight: 700;
  letter-spacing: .2rem;
  text-align: center;
  outline: none;
  cursor: pointer;
  transition: .2s ease-in-out;
  box-shadow: -6px -6px 14px rgba(255, 255, 255, .7),
              -6px -6px 10px rgba(255, 255, 255, .5),
              6px 6px 8px rgba(255, 255, 255, .075),
              6px 6px 10px rgba(0, 0, 0, .15);
}
button:hover {
  box-shadow: -2px -2px 6px rgba(255, 255, 255, .6),
              -2px -2px 4px rgba(255, 255, 255, .4),
              2px 2px 2px rgba(255, 255, 255, .05),
              2px 2px 4px rgba(0, 0, 0, .1);
}
button:active {
  box-shadow: inset -2px -2px 6px rgba(255, 255, 255, .7),
              inset -2px -2px 4px rgba(255, 255, 255, .5),
              inset 2px 2px 2px rgba(255, 255, 255, .075),
              inset 2px 2px 4px rgba(0, 0, 0, .15);
}