.square, .circle  {
 width:200px;
 height: 300px;
 display:inline-block;
}

.circle {
  border-radius: 50%
}

#blockRed {
    background-color: green;
    position:relative;
}

#blockPink {
    background-color:darkmagenta;
    position:relative; 
}

#blockYellow {
    background-color: Yellow;
    position:relative;
}

#container {
    background-color:aqua; margin: 0 auto;
    width:600px; 
}

#blockWood {
    background-image: url('wood.jpeg');
}