<a href="#" class="ctc-liquid"><span>FILTER</span></a>

.ctc-liquid {
  position: relative;
  display: inline-flex;
  align-items: center;
  padding: 10px 22px;
  border: 1.5px solid #00e5ff;
  border-radius: 6px;
  font:
    700 12px/1 ui-monospace,
    monospace;
  letter-spacing: 0.14em;
  color: #00e5ff;
  text-decoration: none;
  overflow: hidden;
  background: #0a0a18;
}

.ctc-liquid::before {
  content: "";
  position: absolute;
  inset: 0;
  right: auto;
  width: 0;
  background: #00e5ff;
  transition: width 0.45s cubic-bezier(0.65, 0, 0.35, 1);
}

.ctc-liquid:hover::before {
  width: 100%;
}

.ctc-liquid span {
  position: relative;
  mix-blend-mode: difference;
  color: #fff;
}