body {

}

#main {
  border: 2px solid black;
  margin: 0px;
  padding: 0px;
  background: #cccccc;
}

.caja {
  margin: 0px;
  padding: 0px;
}

#main td {
  margin: 0px;
  padding: 0px;
}

.caja input {
  height: 35px;
  width: 35px;
  font-size: 20px;
  background-color: #fff;
  text-align: center;
  border: 0;
  color: #0000cc;
}

#botones input {

}