style.css

html, body{
    height: 100%;
}

body{
    margin: 0;
    display: flex;
    justify-content: center;
    align-items: center;
}

.container{
    display: flex;
    flex-direction: column;
    gap: 10px;
    border: 1px solid black;
    width: 410px;
    height: 480px;
    padding: 10px;
    background-color: rgb(48, 48, 48);
}

.display{
    border: 1px solid black;
    display: flex;
    justify-content: flex-end;
    align-items: center;
    flex: none;
    height: 80px;
    background-color: rgb(144, 168, 144);
    font-family: 'Courier New', monospace;
    font-size: 60px;
}

.button-container{
    display: flex;
    gap: 10px;
    flex: 1;
}

.digit-button-container{
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    flex: 2;
    gap: 10px;
}

.operand-button-container{
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    flex-wrap: wrap;
    flex: 1;
    gap: 10px;
}

.digit-button{
    flex: 1;
    min-width: 60px;
    min-height: 60px;
}

.operand-button{
    flex: 1;
    width: 150px;
}

.equal-button{
    flex: 2;
    width: 150px;
    max-height: 89.6px;
}

.ac-button{
    width: 150px;
    flex: 1;
    background-color: rgb(159, 0, 0);
    color: rgb(205, 205, 205);
}

.ac-button:hover{
    background-color: rgb(178, 27, 27);
}

.ac-button:active{
    background-color: rgb(135, 2, 2);
}

.digit-button,
.operand-button,
.equal-button,
.ac-button{
    font-size: 30px;
}

.digit-button,
.operand-button,
.equal-button{
    background-color: rgb(191, 188, 188);
}

.digit-button:hover,
.operand-button:hover,
.equal-button:hover{
    background-color: rgb(208, 206, 206);
}

.digit-button:active,
.operand-button:active,
.equal-button:active{
    background-color: rgb(160, 159, 159);
}