.a {

width:200px;
height:200px;
background-color:red;
    }
    
.b {
width:300px;
height:100px;
background-color:rgba(0,0,255,0.2);
margin-bottom:-50px;
margin-left:100px;
    }
    
    
.t {
    width:300px;
    height:400px;
    background-color:lightblue;
    }