#main-title {
  color: blue;
  background-color: hsl(210, 100%, 50%);
}

.intro-paragraph {
  color: #8A2BE2;
}

#color-box {
  background-color: yellow;
  color: coral;
}

p:not(.intro-paragraph) {
  background-color: rgba(0, 128, 0, 0.3);
}