Hola! Necesito ayuda, tengo que reemplazar selectores?

Cuéntanos qué está pasando:
I see some code that can be optimized. Move the position and top properties and values from .foreground-buildings to .background-buildings . Then select both .background-buildings and .foreground-buildings there, effectively applying those styles to both of the elements. You can use a comma ( , ) to separate selectors like this: selector1, selector2 .

Tu código hasta el momento

:root {
  --building-color1: #aa80ff;
  --building-color2: #66cc99;
  --building-color3: #cc6699;
  --building-color4: #538cc6;
}

* {
  border: 1px solid black;
  box-sizing: border-box;
}

body {
  height: 100vh;
  margin: 0;
  overflow: hidden;
}
.background-buildings{
  width: 100%;
  height: 100%;
  display: flex;
  align-items: flex-end;
  justify-content: space-evenly;
  position: absolute;
  top: 0;
}

.bb1 {
  width: 10%;
  height: 70%;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.bb1a {
  width: 70%;
  height: 10%;
  background-color: var(--building-color1);
}

.bb1b {
  width: 80%;
  height: 10%;
  background-color: var(--building-color1);
}

.bb1c {
  width: 90%;
  height: 10%;
  background-color: var(--building-color1);
}

.bb1d {
  width: 100%;
  height: 70%;
  background-color: var(--building-color1);
}

.bb2 {
  width: 10%;
  height: 50%;
  background-color: var(--building-color2);
}

.bb3 {
  width: 10%;
  height: 55%;
  background-color: var(--building-color3);
}

.bb4 {
  width: 11%;
  height: 58%;
  background-color: var(--building-color4);
}

.foreground-buildings {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: flex-end;
  justify-content: space-evenly;
}

.background-buildings, foreground-buildings {
  position: absolute;
  top: 0;
}

Información de tu navegador:

Desafío: Step 33

Enlaza al desafío:

Hola @deyvioscarzanches ,

Se le pide que elimine estas dos propiedades de .foreground-buildings y las agregue a .background-buildings :

Luego, agregue el selector .foreground-buildings al selector .background-buildings, así :

.selector1, .selector2 {
  ...
}