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

body {
    background-image: url(bg.jpg);
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    
}

.calculator {

    width: 320px;
    background: white;
    padding: 20px;
    border-radius: 12px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, .2);
    border: #217dbb;
    border-width: 50px;

}

#display {

    width: 100%;
    height: 60px;
    margin-bottom: 20px;
    font-size: 28px;
    text-align: right;
    padding: 10px;
    border: 2px solid #ddd;
    border-radius: 8px;

}

.buttons {

    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;

}

button {

    height: 60px;
    font-size: 22px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    background: #3498db;
    color: white;
    transition: .3s;

}

button:hover {

    background: #217dbb;

}

button:active {

    transform: scale(.95);

}

button:last-child {

    grid-column: span 2;
    background: #27ae60;

}

button:last-child:hover {

    background: #1f8a4d;

}

/*Styling*/