style.css

html {
  background-color: #C8E9C5F2;
  margin: 0;
  padding: 0;
  -webkit-user-select: none;
  /* Safari */
  -ms-user-select: none;
  /* IE 10 and IE 11 */
  user-select: none;
  /* Standard syntax */
}

.heading {
  display: flex;
  justify-content: center;
  color: #a91500e0;
}

.ui {
  background-color: #000000;
  width: 100%;
  padding: 0;
  margin: 4px 0 0 4px;
}

button {
  min-width: 80px;
  min-height: 80px;
  border-radius: 10px;
  border: none;
  margin: 2px;
  font-size: 1.8em;
}

.buttons {
  padding: 0;
  margin: 0;
  width: 100%;
  display: flex;
  flex-direction: column;
  justify-items: center;
}

.button-row {
  display: flex;
  flex-direction: row;
  justify-content: center;
}

button.equalbutton {
  color: white;
  background-color: #a91500e0;
  border: 1px solid white;
}

button.clear,
button.delete {
  color: red;
  border: 1px solid white;
  background-color: #FFF10E;
}

button.operatorbuttons {
  color: azure;
  background-color: #03083CF2;
  border: 1px solid white;
}

input.inputdisplay {
  text-decoration: none;
  width: 85%;
  display: block;
  height: 100px;
  font-size: 1.3em;
  border-radius: 10px;
  border: 4px solid indianred;
}

.inputview {
  display: flex;
  justify-content: center;
  margin: 0;
  padding: 0;
  width: 100%;
}