math.css

#question {
  font-size: 250%;
  color: #04ff00;
  display: inline;
}
#timer{
  margin-left: 20px;
}
.footer {
  padding-right: 2%;
  font-size: smaller;
  background-color: #f4c33098;
}

#footer {
  margin-top: 9px;
}

.heading {
  font-size: 200%;
  font-family: 'Courier New', Courier, monospace;
  color: rgb(250, 104, 7);
}

#correct {
  color: green;
}

#incorrect {
  color: red;
}

input::-webkit-outer-spin-button,
input::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

input[type=number] {
  -moz-appearance: textfield;
}

/* above block hides arrows of input field & was copied as is from net */
#level {
  background-color: #a39e8edc;
  border: none;
  color: yellow;
  letter-spacing: 1.5px;
  padding: 9px 32px;
  text-align: left;
  text-decoration: none;
  display: inline;
  font-size: 16px;
  margin: 4px 2px;
  cursor: pointer;
}

.hidden {
  display: none;
}

@media screen and (min-width: 530px) {
  .hidden {
    display: inline;
  }
}