*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    height: 100%;
}

body {
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
}

.main-container {
    height: 54vh;
    width: 54vh;
    font-family: 'Times New Roman', Times, serif;
    background: lightgrey;
    display: flex;
    flex-direction: column;
    gap: 5px;
    justify-content: center;
    align-content: center;
}

.main-container div {
    padding: 4px 15px;
    display: flex;
    justify-content: space-between;
    align-items: baseline;
}

.main-container div button{
    font-size: 20px;
    font-weight: 700;
    background: rgb(165, 163, 163);
    border: 2px solid black;
    border-radius: 15px;
    height: 8vh;
    width: 11vh;
    cursor: pointer;
}

.main-container .add,
.main-container .subtract,
.main-container .multiply,
.main-container .divide {
    background: yellow;
}

.display {
    width: 100%;
    background-color: azure;
    font-size: 24px;
    font-weight: 900;
    text-align: right;
    padding: 10px 15px;
}