* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  background-color: rgb(73, 72, 72);
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

#calc-container {
  background-color: rgb(73, 72, 72);
  padding: 20px 15px;
  width: 450px;
  border: 2px solid rgb(119, 115, 115);
  border-radius: 10px;
}

#display {
  background-color: rgb(85, 83, 83);
  text-align: right;
  padding: 20px 10px;
  color: rgb(224, 218, 218);
  font-family: Monospace;
  font-size: 50px;
  overflow: hidden;
  letter-spacing: 1px;
  margin-bottom: 10px;
}

#buttons-container {
  display: flex;
  flex-direction: column;
  gap: 5px;
  width: 100%;
}

#buttons-container div {
  display: flex;
  justify-content: space-between;
  gap: 5px;
}

#row-4-left {
  display: flex;
  flex-direction: column;
  width: 75%;
}

#equal {
  flex-grow: 1;
}

#zero {
  flex: 1;
}

button {
  width: 100px;
  min-height: 75px;
  cursor: pointer;
  padding: 20px;
  border-radius: 5px;
  display: inline-block;
  border: none;
  font-size: 25px;
  font-family: Monaco;
}

button:hover {
  opacity: 0.9;
  font-weight: bold;
}

button:active {
  opacity: 1;
}

#nine,
#eight,
#seven,
#six,
#five,
#four,
#three,
#two,
#one,
#zero,
#decimal {
  background-color: rgb(153, 153, 144);
}

#add,
#subtract,
#divide,
#multiply {
  background-color: rgb(98, 101, 107);
  color: white;
}

#equal {
  background-color: rgb(88, 93, 94);
  color: white;
}

#clear {
  background-color: rgb(112, 19, 19);
  color: white;
}

#backspace {
  background-color: rgb(40, 40, 40);
  color: white;
}

#add.chosen-operator,
#subtract.chosen-operator,
#multiply.chosen-operator,
#divide.chosen-operator {
  background-color: rgb(105, 101, 107);
}