CSS

align div right

div {
  margin-left: auto; 
  margin-right: 0;
}

div align right in css

#cTask {
  background-color: lightgreen;
}

#button {
  position: relative;
  float: right;
}

#addEventForm {
  position: relative;
  float: right;
  border: 2px solid #003B62;
  font-family: verdana;
  background-color: #B5CFE0;
  padding-left: 10px;
}