Answers for "css background lighten"

css darken

.button {
  color: #ff0000;
}

/* note: 100% is baseline so 85% is slightly darker, 
   20% would be significantly darker */
.button:hover {
  filter: brightness(85%);
}

css lighten function

color: lighten(var(--primaryColor), 50%);

css darken color

// Darker a color
rgba(var(--color-variable), 0.5);