body { 
  text-align: center; 
  margin: 0; 
  background: #f4f0f0d9; 
  display: flex; 
  align-items: center; 
  justify-content: center; 
  height: 100vh;
}
#calculator { 
  max-width: 360px; 
  background-color: #000000; 
  border-radius: 10px; 
  padding: 20px; 
  box-shadow: 0 10px 20px rgba(0, 0, 0, 0.19), 0 0px 0px rgba(0, 0, 0, 0.23);
}
#display { 
  width: 100%; 
  height: 50px; 
  font-size: 20px; 
  text-align: right; 
  margin-bottom: 10px; 
  padding: 20px; 
  border-radius: 5px; 
  color: #000000; 
  background-color: rgba(255, 255, 255, 0.732); 
  border: none; 
  box-sizing: border-box;
}
.operator { 
  color: #000000;
}
#ac { 
  color: #bf4d5d;
}
.equal { 
  width: calc(50% - 10px);
}
button { 
  width: calc(25% - 10px); 
  height: 50px; 
  font-size: 20px; 
  margin: 10px 5px; 
  border: none; 
  border-radius: 5px; 
  float: left; 
  background-color: #fcfff9b3;
  color: #000000; 
  -webkit-box-shadow: -1px 1px 30px -5px rgba(0, 0, 0, 0.2); 
  -moz-box-shadow: -1px 1px 30px -5px rgba(0, 0, 0, 0.2); 
  box-shadow: -1px 1px 30px -5px rgba(0, 0, 0, 0.2);
}