body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #111111;
    color: #e0e0e0;    
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}

button {
    border: none;
    outline: none;
    text-decoration: none;
    box-shadow: none;
    cursor: pointer;
    color: white;
    border-radius: 0;
    font-size: 3rem;
}

#calculator {
    display: grid;
    grid-template-columns: 3fr 1fr;
    grid-template-rows: auto 1fr;
    gap: 0;
    border: 4px solid #8d8d8d;
}

#display {
    grid-column: 1 / -1;
    height: 150px;
    width: 350px;
    font-size: 60px;
    background-color: #333333;
    color: #f5f5f5;
    border: none;
    outline: none;
    text-align: right;
    pointer-events: none;
}

#lSide {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
}

#rSide {
    display: flex;
    flex-direction: column;
}

#lSide button {
    background-color: #4f4f4f;
    transition: background-color 0.1s ease;
}

#rSide button {
    background-color: #666666;
    transition: background-color 0.1s ease;
}

#lSide button:active {
    background-color: #2c2c2c;
}

#rSide button:active {
    background-color: #0077cc;
}