body{
    margin: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    /* background-color: hsl(0,0%,95%); */
    /* background-color: rgb(64, 64, 64); */
    background-image: url(https://images.unsplash.com/photo-1614851099511-773084f6911d?q=80&w=2070&auto=format&fit=crop&ixlib=rb-4.1.0&ixid=M3wxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8fA%3D%3D);
}
#calculator{
    font-family: Arial, sans-serif;
    background-color: hsl(325, 100%, 25%);
    border-radius: 15px;
    border: 4px solid rgb(255, 255, 255);
    max-width: 500px;
    overflow: hidden;

}
#display{
    width: 100%;
    padding: 25px;
    font-size: 5rem;
    text-align: left;
    border: none; 
    background-color: hsl(325, 100%, 19%);
    color: white;
}
#keys{
    display: grid;
    grid-template-columns: repeat(4,1fr);
    gap: 10px;
    padding: 25px;
}


button{
    width: 100px;
    height: 100px;
    border-radius: 50px;
    border:none;
    background-color: hsl(0, 0%, 0%);
    color: white;
    font-size: 3rem;
    font-weight: bold;
    cursor: pointer;
}

button:hover{
    background-color: hsl(351, 64%, 34%);
}

button:active{
    background-color: hsl(292, 94%, 51%);
}

.operator-btn{
    background-color: hsl(345, 98%, 33%);
}

.operator-btn:hover{
    background-color: hsl(265,100%,65%);
}

.operator-btn:active{
    background-color: hsl(265,100%,75%);
}