* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: Arial, Helvetica, sans-serif;
    background-color: #f8f8f8;
}

.calc {
    width: auto;
    margin-top: 30px;
    padding: 0px 10px;
}

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

.button {
    border: 1px solid black;
    width: 100px;
    height: 50px;
    padding: 14px;
    text-align: center;
    margin: 5px;
    font-size: 20px;
    border-radius: 5px;
    user-select: none;
}

.number {
    background-color: lightgrey;
}
.number:active {     
    background-color: darkgrey;    
}

.decimal {
    background-color: lightgrey;
}
.decimal:active {     
    background-color: darkgrey;    
}

.equals {
    background-color: lightblue;
}
.equals:active {     
    background-color: blue;    
}

.clear {
    background-color: lightcoral;
}
.clear:active {     
    background-color: red;    
}

.operator {
    background-color: darkgrey;
}
.operator:active {
    background-color: grey;
}

.display {
    border: 2px solid black;
    border-radius: 5px;
    width: 320px;
    margin-left: 5px;
    text-align: right;
    height: 50px;
    font-size: 22px;
    padding: 12px 10px;
    margin: 5px;
    background-color: lightyellow;
}

.title {
    text-align: center;
    margin-top: 20px;
    user-select: none;
}