.checkbox-liquid {
  position: relative;
  display: inline-block;
}
.checkbox-liquid input {
  display: none;
}
.checkbox-liquid label {
  display: inline-block;
  width: 24px;
  height: 24px;
  background: #333;
  border-radius: 4px;
  cursor: pointer;
  position: relative;
  overflow: hidden;
}
.checkbox-liquid label::before {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 0;
  background: linear-gradient(180deg, #4a90e2, #50e3c2);
  transition: height 0.4s;
  z-index: 0;
}
.checkbox-liquid input:checked + label::before {
  height: 100%;
}
.checkbox-liquid label::after {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%) scale(0);
  width: 14px;
  height: 14px;
  background: white;
  /* Using a checkmark-like shape via clip-path */
  clip-path: polygon(
    14% 44%,
    0% 63%,
    34% 100%,
    50% 82%,
    71% 100%,
    100% 64%,
    80% 44%,
    100% 25%,
    70% 0%,
    50% 18%,
    29% 0%,
    0% 25%
  );
  transition: transform 0.4s;
  z-index: 1;
}
.checkbox-liquid input:checked + label::after {
  transform: translate(-50%, -50%) scale(1);
}