.main{
    position:absolute;
    top:50%;
    left:50%;
    transform:translate(-50%,-50%);
}
.canvas {
  border: solid black 2px;
}
.top, .bottom {
  display: flex;
  flex-direction: row;
  justify-content: space-between;
  margin: 20px 0 20px 0;
}
.block, input, select, button {
  width: 80%;
}
.top>.block{
    margin:10px;

}

.bottom>button{
    margin:10px;
}
.block>p{
    margin:10px auto;
    width:50%;
}