.equation {
    font-size: 2em;
    margin-left: 0.5em;
    margin-right: 0.5em;
}

.centered {
    display: block;
    margin-left: auto;
    margin-right: auto;
    text-align: center;
}

#holdingDiv {
    display: flex;
    justify-content: center;
}
select {
    height: 1.5em;
}
input {
  display: block;
  margin-left: auto;
  margin-right: auto;
  font-size: 3em;
  line-height: 1em;
  border-color: black;
  margin-top: 0em;
  width: 7em;
  height: 1.5em;
}
.equationP {
    margin: 0.5em;
    margin-top: 0.2em;
}
#red {
    color: red; 
}