a {
  background-size: cover;
}

b {
  background-size: contain;
}

c {
  background-size: auto;
}

d {
  background-size: auto auto;
}

e {
  background-size: auto 100%;
}

f {
  background-size: 100% auto;
}

g {
  background-size: 100%;
}

h {
  background-size: auto 10px;
}

i {
  background-size: 10px auto;
}

j {
  background-size: 10px;
}

k {
  background-size: 10px 100%;
}

l {
  background-size: 100% 10px;
}

m {
  background-size: 10px 10px;
}