body {
  font-family: Arial, sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
  background: #f4f4f9;
  background-image: url(https://wallpapercave.com/uwp/uwp4198368.jpeg);
  background-repeat: repeat;
  background-position: center;
  background-size: cover;        
}

.container {
  background: #FFCF9D;
  padding: 20px;
  border-radius: 10px;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.2);
  width: 300px;
  border: outset;
}

/* Screen area */
.screen {
  background: #FFF9BF;
  border: ridge;
  border-radius: 5px;
  padding: 5px 10px;
  margin-bottom: 10px;
  text-align: right;
  overflow: hidden;
}

#expression {
  font-size: 1em;
  color: #333;
  height: 20px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

#result {
  font-size: 1.8em;
  font-weight: bold;
  height: 40px;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
}

button {
  height: 50px;
  font-size: 1.2em;
  border: solid;
  background: #CB9DF0;
  color: #fff;
  border-radius: 5px;
  border-color: #dedee7;
}

button:hover {
  background: #A2D2DF;
}

button.equal {
  grid-column: span 1;
  grid-row: span 2;
  height: 100%;
}

button:active {
  transform: scale(0.95);
}