Learn CSS

CSS Syntax

selector { property : value; }

/****************Tag Selectors************/
h1{
  color: red;
  font-size: 200px;
}

img:hover {
  background-color: gold;
}

/****************Class Selectors************/
.bacon{
  background-color: red;
}

.broccoli{
  background-color: red;
}

.circular{
  border-radius: 100%;
}

/****************ID Selectors************/
#heading{
  color: blue;
}

#big{
  font-size: 1000px;
}

Coding Reference
Developer.Mozilla.Org