body{
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    height: 100vh;
   margin: 0;
   padding: 0;
   font-family: Arial, Helvetica, sans-serif;
   background-color: #1c1b1b;

}

h1{
    color: #fff
}

.calculator{
    background-color: #fff;
    padding: 20px;
    border-radius: 10px;
    width: 300px;   
}

#display{
    width: 100%;
    box-sizing: border-box;
    height: 60px;
    border: none;
    border-radius: 6px;
    background-color: #f0f0f0;
    text-align: right;
    font-size: 20px;
    margin-bottom: 16px;
}

.box-buttons{
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    grid-template-rows: (4, 1fr);
    gap: 10px;   
}
button{
    border: none;
    height: 60px;
    border-radius: 6px;
    font-size: 20px;
}

button:hover{
    background-color: #e1e1e1;
    cursor: pointer;
    transition: 400ms;
}

.btn-zero{
    grid-column:  1 / 3;
}

.btn-result{
    grid-row: 4 / 6;
    height: 100%;
    grid-column: 4;   
}