*{
	  box-sizing: border-box;
	}

	#contenedor{
	  width: 900px;
	  height: 450px;
	  margin: auto;
	  border: 5px solid black;
	  display: flex;
	}

	#izquierda{
	  flex: 2;
	  border-right: 5px solid black;
	}

	#derecha{
	  flex: 3;
	  display: flex;
	  flex-direction: column;
	}

	#fila-superior{
	  display: flex;
	  height: 33%;
	}

	#arriba1{
	  flex: 2;
	  border-bottom: 5px solid black;
	  border-right: 5px solid black;
	}

	#arriba2{
	  flex: 1;
	  border-bottom: 5px solid black;
	}


	#fila-medio-inferior {
	  display: flex;
	  flex: 1;     
	  height: auto;
	}
	
	#medio-vertical {
	  flex: 1;
	  border-right: 5px solid black;
	  border-bottom: 1px solid black; 
	  height: 100%; 
	}

	#columnita {
	  flex: 2;
	  display: flex;
	  flex-direction: column;
	}

	#abajo-horizontal1 {
	  flex: 1;
	  border-bottom: 5px solid black;
	}

	#abajo-horizontal2 {
	  flex: 1;
	}


	@keyframes girar {
	  from { transform: rotate(0deg); }
	  to { transform: rotate(360deg); }
	}

	.volver {
	  position: fixed;
	  bottom: 20px;
	  left: 20px;
	  text-decoration: none;
	  font-weight: bold;
	  color: black;
	  font-size: 18px;
	}

	.volver:hover {
	  animation: girar 1.5s linear infinite;
	  transform: scale(1.15);
	}

	.pie {
	  position: fixed;
	  bottom: 20px;
		right: 20px;
	  font-weight: bold;
	  font-size: 18px;
	}