* {
    margin:0;
    padding:0;
    box-sizing:border-box;
}
body{
    background-color:#1e1e1e;
    min-height:100vh;
    display:flex;
    justify-content:center;
    align-items:center;
    font-family:Arial,sans-serif;
}
.calculator{
    background-color:#2d2d2d;
    padding:20px;
    border-radius:12px;
    width:320px;
}
.display{
    background-color:#111;
    color: #f4f0f0;
    overflow-x:auto;
    white-space:nowrap;
    padding:20px;
    margin-bottom:15px;
    text-align:right;
    font-size:2rem;
    border-radius:8px;
}

.buttons{
    display:grid;
    grid-template-coloumns:repeat(4,1fr);
    gap:10px;
}

button{
    padding:20px;
    border:none;
    border-radius:8px;
    background-color:#444;
    color:white;
    font-size:1.2rem;
    cursor:pointer;

}
button:hover{
    background-color:#555;
}
.zero{
    grid-column:  span 4;
}