.calculator {
    margin: auto;
    width: 250px;
    max-width: 100%;
    padding: 10px;
    border: 1px solid black;
    border-radius: 10px;
    box-shadow: 2px 2px 2px grey;
    background-color: #f2f2f2;
}

#result {
    width: calc(100% - 20px); /* 20px = left and right padding of calculator */
    max-width: calc(100% - 20px); /* set max width to be less than calculator's width */
    margin-bottom: 10px;
    padding: 10px;
    font-size: 24px;
    text-align: right;  
    display: flex;
  justify-content: flex-end;
  align-items: center;
}

.button-row {
    display: flex;
    justify-content: space-between;
    margin-bottom: 5px;
}

button {
    width: 50px;
    height: 50px;
    border: none;
    border-radius: 5px;
    background-color: #e6e6e6;
    color: black;
    font-size: 24px;
    cursor: pointer;
  transition: all 0.2s ease-in-out;
}


.button.press {
  transform: translateY(1px);
  box-shadow: 0px 2px 2px rgba(0, 0, 0, 0.25);
}

.button:focus {
  outline: none;
  box-shadow: 0px 0px 5px rgba(0, 0, 0, 0.3);
}



.operator {
    background-color: #ff9933;
    color: white;
}

.equal {
    background-color: #1abc9c;
    color: white;
}

.zero {
    width: 100px;
}

.delete {
    background-color: #ff3333;
    color: white;
}